Q: I have a 20-year-old Arabian/Paint gelding that I’ve had since he was 3 months old. He was always an easy keeper and I realized when he was around age 4 or 5 that he had equine metabolic syndrome (EMS).

From that day on, he’s consumed low-nonstructural-carbohydrate (NSC) hay and grain. Because he is an air fern, I’m always careful about what he eats and severely limit his grazing time; I keep him on a dry lot most of the time. At age 14 he developed pituitary pars intermedia dysfunction (PPID, formerly called equine Cushing’s disease). My veterinarian put him on 1.5 Prascend (pergolide) pills per day, which I administer in addition to Thyro-L (levothyroxine sodium).

Somewhere during all of this, my gelding started losing weight. He had a mild gastric ulcer attack a few years ago, so my veterinarian prescribed ranitidine, which she later replaced with cimetidine. Recently, he had another ulcer attack and currently has omeprazole added to his diet. My question is, how do you feed PPID, EMS, and ulcer-prone horses that need to gain weight? I already feed every four to five hours. Consuming oils never helped him, but soaked beet pulp has helped some.

A: Hello, I am sorry you’re having to handle these difficult issues. The first thing I recommend is having a good discussion with your veterinarian about your horse’s conditions to determine whether the current medications should stay the same or be adjusted. Veterinarians often prescribe Thyro-L to help horses regulate glucose and insulin and treat EMS. They also commonly prescribe Prascend, which you also mentioned, for horses with PPID. Both medications can cause weight loss—a side effect that usually benefits horses with EMS and PPID. However, your veterinarian might want to monitor the dosage and make adjustments if needed.

I am glad to hear your horse receives omeprazole for his ulcers. Currently it is the only FDA-approved medication for treatment and prevention of gastric ulcers in horses. I recommend talking with your veterinarian about whether you can discontinue this medication or reduce the dosage once management strategies help get the condition under control.

I would like to address feeding management of the three distinct disorders you mention—EMS, PPID, and gastric ulcers. Fortunately, some of the recommendations for managing these conditions overlap, which can make caring for your horse easier.

EMS

Horses with EMS tend to be easy keepers and carry extra weight, but you need to make sure you aren’t “starving” them to get them to an ideal weight. Forages low in NSCs should be the base of their diet. Typically, they should have only hay with little to no access to pasture, especially in fall and spring when pasture NSC levels tend to be higher. On a per-pound basis you’ll want to avoid feeding less than 1.5% of a horse’s body weight in hay. A low-calorie/low-sugar ration balancer can help you make sure you meet all his nutritional requirements. To help keep glucose and insulin levels steady, provide small, frequent meals and/or use a grazing muzzle to slow down feed intake.

PPID

Pituitary pars intermedia dysfunction cannot be managed with diet alone (hence, giving pergolide), but it can help. Overweight horses should receive a lower-calorie diet to promote weight loss, and horses with insulin resistance or insulin dysregulation (often referred to together as EMS), need a diet low in NSCs. If a horse with PPID has not been diagnosed with EMS, you can generally feed a balanced diet of forage and concentrates or a ration balancer, while monitoring weight to prevent excessive gain.

Gastric Ulcers

For horses prone to gastric ulcers, feeding recommendations try to decrease acidity (low pH) in the stomach. Horses are designed to be continuous feeders; some type of feed is in the stomach almost constantly. We can mimic this by providing horses with multiple small meals throughout the day and allowing free-choice access to forages. Nutritionists also recommend reducing the amount of concentrate a horse receives to address gastric pH. Higher-fat feeds tend to slow gastric emptying rate and are not as acidic as more traditional concentrates. Experts also suggest offering some feeds on the market that contain more complex carbohydrates. Adding a forage higher in calcium might also be beneficial, because it works as a natural antacid.

With both PPID and EMS the goal is to keep insulin levels regulated and maintain a horse’s body weight at a level that won’t predispose him to bouts of laminitis. I recommend you feed a good-quality mostly grass hay with an NSC level of less than 10%. If you can’t find hay with NSC levels below 10%, soak the lowest-NSC hay you can find for about 30 minutes prior to feeding to help reduce the sugar and starch content. Remember that you should not give your horses access to the soaking water because it will have all those undesirable carbohydrates in it. You should feed your horse about 2% of his body weight in forage daily—so about 20 pounds of hay for the average 1,000-pound horse.

I would also recommend a ration balancer if your horse maintains his weight on forage alone. Essentially, manufacturers design balancers to work as a vitamin and mineral supplement to ensure your horse gets the correct levels he needs. Make sure it is low in soluble carbohydrates. If he cannot maintain his weight on forage alone, then I recommend one of the higher-fiber feeds available. You mentioned your horse has consumed beet pulp, and it helped, whereas fats did not. Fortunately, many of these feeds have a beet-pulp base. These recommendations also work for the ulcer-prone horse, so they might help there as well.

It sounds like you are already taking many of the right steps for managing a horse with these three issues. Keep feeding meals more frequently and make sure you’re using low-NSC forages and feeds to maintain an appropriate body weight for your horse. I would be interested to hear what your veterinarian recommends related to the medications, and I wish you the best of luck.

Do you have an equine nutrition question?

Q. I feed my ulcer-prone horse alfalfa before riding, because I’ve heard the calcium in alfalfa works like a big Tums antacid to keep my horse’s stomach from hurting during exercise. I was recently told that alfalfa pellets don’t work and that I should use alfalfa hay or chop instead, because the alfalfa needs to create a “hay mat” in the stomach to keep acid from splashing up into a horse’s esophagus (basically, causing horse heartburn). Is it true that I need to feed alfalfa hay or chop instead of pellets?

A. You are correct. Alfalfa is typically high in calcium, which researchers have shown reduces stomach acidity due to its buffering capacity. In a study at Texas A&M University, 12 horses were assigned to one of two groups: a 1:1 ratio by weight of Bermuda hay and a concentrate feed or of alfalfa hay and the same concentrate feed.

Treatment periods lasted 28 days before horses switched to the other diet with a 21-day washout period between treatments. At the start of the study each horse went through a gastroscopy to determine whether they had gastric ulcers and, if so, their severity. Horses were rescoped after the 28-day treatment periods to determine whether any existing ulcers had improved or worsened or new ulcers had appeared.

The researchers found that ulcer severity scores were significantly lower when horses ate alfalfa hay compared to Bermuda hay. Feeding alfalfa prevented ulcer formation in 11 of 12 horses that did not have ulcers initially, whereas only three of the 12 horses that did not have ulcers stayed ulcer-free when fed Bermuda. The team attributed these results to alfalfa’s higher calcium and protein content providing greater buffering capacity. The complex carbohydrate fractions found in alfalfa’s cell walls have also been shown to provide better buffering than those found in grass hays.

It’s clear that alfalfa does a good job of buffering the acid in the equine stomach. The question therefore becomes, does it matter what form the alfalfa is in? Long-stem hay requires a good amount of chewing before being swallowed, and chewing results in saliva. Equine saliva contains a good amount of sodium bicarbonate, which will also buffer stomach acid. Pellets take less chewing so result in less saliva and lower buffering from the bicarbonate. So long-stem hay would be preferable from that perspective. But what about the fiber mat?

The equine stomach is not completely full of acid. Large feed particles float on top of the acid, helping prevent it from splashing into the upper portion of the stomach where most ulcers occur. Pellets have a much smaller particle size than long-stem fiber, so alfalfa hay is more likely to make a better mat than pellets. Keep in mind that any forage in hay form—not just alfalfa—will form a good mat and cause saliva production. So if your horse has eaten hay within the few hours prior to your ride, he likely already has a good mat.

The calcium in pellets might buffer more quickly than hay due to the smaller particle size, but the smaller particles might also cause the calcium to move out of the stomach faster than larger particles would. So the question becomes: Which is more important, the hay mat or the buffering? If the stomach’s acidity is low, it won’t matter as much if the acid splashes into the stomach’s unprotected upper region. A hay mat is less important when the stomach acid is less acidic, and depending on when your horse last ate hay, a mat might already exist.

If you’re arriving to ride your horse and he has an empty stomach, and you give him alfalfa while you’re grooming, he might not have time to consume much alfalfa hay, because it requires more chewing. You might get greater buffering capacity more quickly by feeding pellets, although you won’t get a great mat. Most stomach buffers are relatively short-lived, lasting at most a couple of hours. Research has shown that some commercial buffers on the market buffer effectively and more quickly than alfalfa. These can be great options when given before exercise, if you need buffering capacity quickly.

Alfalfa’s ability to help reduce ulcers, and in which form you should use it, depends on a combination of complex interactions. The best solution for each horse might not be completely clear, but what we do know is that giving some form of alfalfa before riding a horse with an empty stomach will likely have a positive impact and could reduce your horse’s risk of developing gastric ulcers.

Skippy was almost aptly named. He didn’t skip, but he did hop and jump. And to his owner’s great regret, Skippy bucked.

“He was a horrible ride,” recalls Amber Cash of Newark, Delaware. “He kicked, he bucked, he bit, he would run and not stop. I thought I could train it out of him, but he always seemed angry.”

Skippy wasn’t always like that, though. Often—and especially when he didn’t have a rider—the big red gelding was delightful, which made Cash suspect his bucking was pain-related. “He was loving, funny, smart, and playful,” she says. “But when he hurt, he was a holy terror.”

Cash tried dozens of saddles, stretching techniques, and chiropractors, all to no avail. It wasn’t until she got his back radiographed that she discovered the tips of her horse’s backbone were running into each other—a condition known as kissing spines. After surgery to create more space between the vertebrae, Skippy was a changed horse. “He was so much happier and easy to ride,” says Cash.

Bucking Basics

The buck evolved in horses as a defense mechanism to literally throw off predators, says Sue Dyson, MA, VetMB, PhD, an independent consultant in the UK, who published a scientific review on bucking research in 2021.

A few other herbivores, such as sheep and antelope, have a certain kind of buck, she says. But the equine buck takes the skill to new heights: Their leaps into the air, with two or four legs off the ground, sometimes combined with either an arched-up or stretched-out back, the head low, and/or sudden stops and twists, could pitch off just about any animal—­including humans.

What Kind of Buck Is It?

Not all bucks are created equal, says Dyson. Some include little hops with the upper back—the thoracic spine, from the wither to the loin—in extension and the head up; some involve full flying leaps with the back up and the head down (“pronking” or “crow-hopping”); some propel rapidly forward in a series of pronks (“bronking”), often with lots of stops and twists.

“I always ask my clients, ‘Do you feel the horse is trying to buck you off?’ ” Dyson says. “If they say no, that’s a completely different situation from the horse that does the kind of rodeo act when its back is in flexion all the time.”

Our sources agree that most horses that buck consistently merit a visit from the veterinarian. Even if your horse isn’t throwing you off, his body language is likely telling you something’s wrong, and he needs help.

We’ve listed nine reasons horses buck—most of which are pain-related. Bucking seems to be a natural equine response to pain, although the biological reason for that remains unclear. “We can’t necessarily say it’s pain relief, but it’s definitely a reaction to pain,” says Dyson.

1. Kissing Spines

When the long points sticking up from the top of vertebrae—known as spinous processes—crowd each other, they’re said to be “kissing.” Bone hitting bone is painful, especially with added pressure from a rider, says Beau Whitaker, DVM, of the Brazos Valley Equine Hospital, in Salado, Texas. “The No. 1 thing I look for in bucking horses is kissing spines,” he says.

Kissing spines in the saddle area (the caudal thoracic and the lumbar spines) are the most likely to cause discomfort that can lead to bucking, he says. “When you get on the horse, it causes the back to drop and the spine to ventroflex (extend), and that pushes those bones even closer together, causing more pain, so the horse starts to buck.”

Not all horses with radiographic evidence of kissing spines, however, display signs of pain such as bucking.

2. Sacroiliac Joint Pain

The large, rigid sacroiliac joints lie between the ilium of the pelvis and the sacrum (the vertebral column from the loin to the tail—also considered a part of the pelvis) and are supported by ligaments above and below. Through wear or injury, horses can damage these joints and ligaments—and the result is often a very telltale kind of buck, says Dyson.

“They usually only buck when ridden, not on the longe,” she says. “They buck with their back extended, most commonly in canter, and may kick out backward or sideways. As a rider, you don’t feel like they’re trying to get you off.”

Her recent postmortem work for a soon-to-be-published study has shown that some of these horses even have a damaged obturator or sciatic nerve, which could lead to neuropathic pain (caused by damage to specific nervous system regions that perceive pain).

3. Gastric Ulcers

Bucking-related pain can also come from the stomach, says Whitaker. Sixty to 90% of adult performance horses have gastric ulcers, which develop when digestive acids break down the stomach lining, often due to stress, large amounts of concentrate feeds, and/or long breaks between meals.  

“Some horses get enough pain from gastric ulcers that when they’re moving, especially cantering, that acid starts to splash around and irritate them, making them buck,” he says. Gastroscopy is the only way to confirm a horse has ulcers, so it’s a useful procedure when other pain has been ruled out.

4. Poorly Fitting Tack

A saddle that’s incorrectly fitted or badly positioned on your horse’s back can concentrate high pressures in a small area or pinch, such as just behind the withers, Dyson says. Some horses have a “bucking spot” behind the saddle: Firm pressure to this area might trigger bucking.

A broken tree can also cause a horse to react, says Whitaker, as can a poorly fitted saddle pad or tack such as breastplates, bridles, and bits.

Girths can also be culprits, says Dyson, particularly those with elastic inserts. Some horses might find the moving elastic uncomfortable.

5. Other Sources of Pain

Bucking-associated pain can come from all over the body, our sources say. For example, they’ve found it in the pelvis, limbs (especially the hocks and stifles), and ribs. “Lameness may be the cause of bucking,” says Dyson.

Or it might come from the other end of the horse: “Sometimes they’ll have a hook or a fractured tooth,” says Whitaker. “This can hurt more when they get their heads in a certain position. Often those horses will throw their heads, but we do see some that manifest in ways you wouldn’t expect, like bucking.”

Dyson says she has seen bucking related to a torn ligament in the back, spondylosis (degenerative bone changes) of the spine under the saddle, and a broken sternum, among other orthopedic issues.

6. Fear

In some circumstances, the consequences of a horse’s buck—namely, the rider falling off—can scare them. “You see some horses, when they’ve bucked the rider off, they just stand there and act absolutely astonished and fearful,” Dyson says. “They are often terrified of being remounted, (and they may especially) not tolerate the rider sitting upright.”

This doesn’t mean the horse is afraid he’s “done something wrong,” which is too anthropomorphic, she says. Rather, the horse is fearful of having a mass projected over its head.

7. Accidental Buck Training

Whether they’re frightened or anticipating pain, or they just don’t like being ridden—maybe due to previous bad experiences—some horses learn that strong bucking gets rid of the rider and any related pain. That relief is a strong reward, and they learn to buck to get it.

Even after veterinarians perform therapy to relieve a bucking horse’s pain, he might continue to buck because he learned to when it hurt to be ridden. “Unless something changes, like an intervention from a behavioral management point of view, you may get into a situation which spirals out of control,” Dyson says.

Unskilled riders can start the spiral, she says. Riders with poor balance might bounce a lot (causing pain) and eventually fall with a simple buck. And some horses develop a tendency to buck early in a riding session, which could be the result of having quickly dislodged novice riders.

Learned bucking is often more difficult to resolve than pain-related bucking, our sources say. “Sometimes you have to try to work those horses through the mental aspect of it, once you get past the pain aspect,” Whitaker says. “And that’s not always easy to figure out.”

8. Intentional Buck Training

It’s worth mentioning, of course, that some horses are purposefully trained to buck. “Certain lines of horses, from a rodeo performance point of view, are apparently better at bucking,” Dyson says. Usually, when they don’t have cinches around their groin, they won’t buck, she adds. However, they might have a greater propensity for it.

Meanwhile, some high-level dressage horses, such as from the Spanish Riding School in Vienna, Austria, are taught bucklike movements such as the capriole.

9. Feeling Great!

Bucking can represent both negative and positive feelings. Horses buck out of exuberance when galloping and playing at pasture and sometimes under saddle, says Dyson. “They can feel fresh and exuberant, like when you take them out to the beach to gallop, and they give some happy bucks,” she says.

There’s a stark difference between the happy buck and the buck that says something’s wrong, however. Feel-good bucks are usually one-shots in specific situations of excitement, whereas bucks in a series or that happen every time you ride should raise a red flag.

Happy bucks aren’t usually an issue—unless you’re not skilled enough to ride them out, Dyson says. However, horses can be trained to not buck under a rider, even when they’re exuberantly happy.

Getting an Evaluation

If you’ve got a bucker, get your horse—and your tack—evaluated. Have a master saddler check your saddle and bridle, and ask your veterinarian to run a buck evaluation. That usually starts with palpating the back to check for reactions to pain, followed by radiographs and, if necessary, a gastroscopy, says Whitaker.

Veterinarians should also evaluate the horse in hand, while longeing, and under saddle (if he’s safe to ride), says Dyson. Local (temporary) nerve blocks can help find the part of the body that’s hurting.

Sometimes veterinarians perform an ultrasound of a painful area to see if the soft tissues have been affected. If those checks don’t lead them to the problem, practitioners might pursue bone scans (scintigraphy) to look for inflammation in the bones. Bone scans can help veterinarians track improvement once horses have started therapy, Whitaker says.

Treatment must be targeted depending on the diagnosis, says Dyson. Most horses also need behavioral retraining after they’ve recovered physically, to learn not to buck once the pain is gone. Seek the help of a certified behaviorist or a trainer versed in positive reinforcement methods.

Take-Home Message

Bucking might be what happy horses do in a field, but it can spell trouble when they’re doing it repeatedly under saddle. Veterinary treatment and behavior management can help resolve the issues behind the buck, our sources say. And when you identify the reason for the buck—like Cash did for Skippy—it can be a game-changer for both horse and owner.

Mean glandular severity scores were significantly lower in the treatment group on Days 28 (shown) and 35, as seen on gastroscopy exam. | Courtesy Dr. Frank Andrews

Equine gastric ulcer syndrome (EGUS) refers to any ulceration inside a horse’s stomach. It often causes severe physical pain, leading to clinical signs such as behavior changes, weight loss, and loss of appetite.

Veterinarians view omeprazole as the mainstay EGUS treatment, said Frank Andrews, DVM, MS, Dipl. ACVIM, LVMA equine committee professor of equine medicine and director of equine health and sports performance at Louisiana State University’s School of Veterinary Medicine, in Baton Rouge. He spoke on the subject at the 2024 American Association of Equine Practitioners Convention, held Dec. 7-11, in Orlando, Florida. But because omeprazole might not be suited for long-term use, he said he and his team studied a schizophyllan—a beta-glucan—and hyaluronan product (relyneGI) to see if it could be useful in caring for ulcery horses.

Schizophyllan and Hyaluronan

Hyaluronan is a high-molecular-weight glycosaminoglycan in joint, intestinal, and gastric tissues. “It functions to maintain gastric and intestinal homeostasis, innate immunity, and modulates inflammation,” said Andrews. “In rats—which have a similar stomach to a horse with a squamous and glandular region—hyaluronan has been proven to protect the gastric lining and improve gastric mucosa integrity.”

Beta-glucans are an integral part of cell walls; schizophyllan activates immune cell maturation, differentiation, and proliferation. They have prebiotic properties and have been proven safe for use in horses.

Andrews and his team studied the efficacy of the new schizophyllan and hyaluronan gastric support supplement in 12 stall-confined Thoroughbred and Thoroughbred-cross horses with naturally occurring gastric ulcers. They divided horses evenly into treatment and control groups, performed gastroscopic exams, and weighed each horse at the start of the study after two days of acclimatization.

Over the 35-day treatment period the team gave 1 ounce (the high-stress dose) of the supplement three times daily in each treatment group horse’s feed and a 1-ounce dose of placebo three times daily in each control horse’s feed. They were blinded to treatments to avoid bias in scoring and repeated gastroscopies and weight checks on Days 14, 28, and 35.

Supplement Effects on Gastric Ulcer Scores

Andrews and his team saw a significant weight increase in all horses, but the treatment did not affect body weight. The mean nonglandular EGUS and severity scores were significantly lower in the treatment group on Days 28 and 35.

“The nonglandular ulcers were healed, except for mild hyperkeratosis (callousing), on these dates as well,” Andrews said. “The mean glandular (ulcer) and severity scores were significantly lower after 14 days in the treatment group. The ulcers did heal, but some reoccurred in both groups of horses by Day 28, which is not uncommon in these types of ulcers.” The mean gastric fluid pH remained low and variable throughout the study in both groups. Many drugs when used long term block gastric acid, which can change the stomach’s physiology. In other words, this supplement contributed to gastric health without changing stomach acidity.

Take-Home Message

Based on the research, Andrews said he believes the schizophyllan and hyaluronan supplement might have uses for managing horses with EGUS long-term and/or in conjunction with appropriate pharmaceutical treatment. (Supplements shouldn’t be used to treat disease but improve stomach health after discontinuing pharmacologic agents, he added.) The researchers observed clear improvement in nonglandular and glandular ulcer scores in the treatment group and did not observe any adverse effects from the supplement. The horses also readily consumed it, he added.

Andrews noted study limitations were a small sample size with limited breeds, a short treatment period, and that horses were stalled without exercise—management approaches that can be risk factors for ulcers. He hopes to address these limitations in future studies by finding out if the schizophyllan and hyaluronan product acts synergistically (a combined positive effect) with omeprazole or other drugs to improve gastric health in horses as well as prevent gastric ulcer recurrence.

Gastric ulcers are sores in the equine stomach lining that cause distress and negatively affect performance. An estimated 60% of performance horses and 90% of racehorses have gastric ulcers. The odds of a horse developing gastric ulcers increase with stress such as exercise or life changes.

“Such stresses include training, trailering, and showing … all things we do with our horses all the time, putting our horses at risk,” said Jyme Nicols, PhD, director of nutrition for Bluebonnet and creator of the Feed Room Chemist Podcast during her presentation at the 2024 virtual EquiSummit, held Dec. 3-4.

Where Do Equine Gastric Ulcers Occur?

Horses have one very small (3- to 5-gallon) single-chambered stomach, which functions best when they are allowed to eat small amounts of food all day. The stomach is made up of two key areas: an upper area covered by squamous tissue and a lower covered by glandular tissue. The lower glandular region produces acidic gastric juice and mucus.

“It is very important to know where ulcers are—the squamous, glandular, or both—because location will influence treatment protocol,” said Nichols. “And the only way to diagnose ulcers is to have the horse ‘scoped’ by a veterinarian,” meaning with the use of a gastroscope.

How to Score Equine Gastric Ulcers

In 1999 researchers introduced the term equine gastric ulcer syndrome (EGUS) as an umbrella term for any ulcer in the horse’s stomach. Experts later reported that ulcers in the glandular and squamous region are very different, and the two types should be described independent of one another.

For squamous ulcers, in the upper region of the stomach, veterinarians use a well-established grading system, which describes ulcers based on severity. The scale ranges from 0 (healthy with no ulcers) to 4 (extensive lesions, deep erosions). In contrast, practitioners have no universal scoring system for glandular ulcers (in the lower region of the stomach). Instead, they describe those ulcers based on their physical appearance and specific location (e.g., nodular, flat, raised, depressed, and in the antrum, pylorus, etc.).

Causes and Risk Factors for Equine Gastric Ulcers

“As mentioned above, we ask horses to do things they aren’t designed to do such as training, trailering, and showing,” said Nichols. “They are designed to have their heads down, grazing, in a herd, yet we isolate them in stalls, travel, and hire trainers to work with them. We often feed them meals only twice a day, sometimes with large amounts of grain, and many owners don’t have the luxury of turning their horse out all day.”

Some key risks factors for developing EGUS include:

• Extended periods without forage. Going six hours or more between forage meals (hay or pasture) increases a horse’s risk, and many horses are going beyond six hours, said Nichols. Extending feeding time and ensuring horses have forage available at all times can help decrease the risk.
• Insufficient water. Water serves as an excellent buffer for gastric juices, and horses that drink well and always have access to water at all times are less likely to develop gastric ulcers. In contrast, horses with restricted water access are more than two times more likely to have ulcers.
• Consuming high-starch meals exceeding 2 g/kg of bodyweight doubles the horse’s risk of developing ulcers.
• Medications such as non-steroidal anti-inflammatory drugs (NSAIDS, e.g., phenylbutazone and flunixin meglumine) increase the risk of glandular disease especially, by damaging the gastric mucosal lining.

Clinical Signs of Equine Gastric Ulcers

 “Signs of EGUS can be subtle, so you have to know your horse and what is normal in order to recognize what is abnormal,” said Nichols.

Subtle behavior changes, such as changes in facial expression when saddling (ear, eye, and mouth position and movements), can suggest the presence of gastric ulcers. Other signs of EGUS can include general irritability and girthiness (e.g., the horse might try to bite cross-ties or you, swish his tail) and changes in performance.

Certain indicators of ulcers can become more apparent, such as dropping condition, losing topline, dull haircoat, and exhibiting signs of colic.

Diagnosing and Treating Equine Gastric Ulcers

Always have your veterinarian perform a gastroscopy on your horse if you think he might have gastric ulcers.

“Be aware that there is no link between glandular and squamous disease,” said Nichols. “Having one does not mean they do or do not have the other. Plus, there is no link between outward signs and the severity of ulcers.”

Treating ulcers mainly involves suppressing acidity in the stomach and protecting the gastric mucosal lining. The most commonly prescribed medications include omeprazole, ranitidine, and sucralfate.

“We also need to consider what led to ulcers in the first place,” said Nichols. “Align their daily lives with how they are physiologically designed—let your horse be a horse.” Management changes such as increasing forage available, reducing stressors in the environment, and limiting changes in routine can help decrease your horse’s risk of developing gastric ulcers.    

Take-Home Message

“Be aware that most horses are at risk of developing gastric ulcers, so pay attention to your horse’s behavior to appreciate early signs,” Nichols said.

Prevent gastric ulcers whenever possible by managing your horse’s diet, the environment, and his stress levels, and work closely with your veterinarian and equine nutritionist to diagnose, treat, and manage EGUS.

Additional 2024 EquiSUMMIT Coverage:

• Rules for Feeding Horses Forage
• Investigating Prebiotics’ Role in Managing Equine Leaky Gut
• Benefits of Extruded Horse Feeds
• What Happens With the Horse’s Gut in the Heat?
• The Equine Microbiome and Immunity

Q: Is it okay to feed my horse peppermints and sugar cubes? I’m concerned about the amount of sugar they contain. If it is okay, how many is too many?

A: Simple sugars, such as the sucrose found in peppermints and sugar cubes, are absorbed by the horse’s small intestine as glucose and fructose. Glucose causes release of insulin to facilitate the entry of glucose in to cells. Fructose (not to be confused with fructans) is metabolized differently. Only metabolized in the liver, fructose is more lipogenic than glucose, meaning that it’s more likely to lead to production of fat.

Most concern about sugar and starch intake has stemmed from our increasing knowledge about insulin resistance (IR), laminitis, polysaccharide storage myopathies (PSSM), and equine gastric ulcer syndrome (EGUS). Horses with IR release more insulin than is normal in order to remove glucose from their blood stream. As a result, while circulating glucose tends to be normal, circulating insulin is elevated. High circulating insulin creates an increased risk for developing laminitis. Horses with PSSM store glycogen (the storage form of glucose) abnormally in their muscle tissue, and diets high in starch and sugar cause increased production of volatile fatty acids in the gastric stomach causing a more acidic environment and a greater likelihood of a horse developing EGUS

I think it’s important to put the questions of sugar in treats in perspective of a horse’s typical daily non-structural carbohydrate consumption. If we assume a 1,200-pound horse eating 2% of body weight as dry matter from hay a day, and that the hay contains 10% moisture and 10 % nonstructural carbohydrate (NSC) on a dry-matter basis (a value often used as the recommended upper NSC level for horses with metabolic issues, such as IR and PSSM), this horse is consuming 1,090 grams of NSC (starch and simple sugars) per day.

A pure sugar cube weighing about 4 grams is 100% sucrose. The popular round, red-and-white peppermint candies have a human serving size of three pieces (about 15 grams) and of that between 8 and 10 grams are sugar. Traditional peppermint candy canes are heavier at 18 grams and provide about 12 to 14 grams of sugar. You can see that in the context of the above horse’s daily diet these are tiny intakes of sugar. However, there are some important considerations.

When feeding a horse hay, you’re also feeding it proteins and minerals that help buffer stomach acid. Additionally, hay’s fiber component impacts the rate at which the NSC reaches the small intestine and is absorbed. The sugar in sugar cubes dissolves quickly and will move with the liquid fraction of the digesta, which moves more rapidly than larger fibrous particles. This means that that the sugar will likely be absorbed relatively soon after it is fed. This makes it potentially more likely to cause a spike in blood glucose than the NSC contained within hay.

Feeding a healthy horse three or four sugar cubes is unlikely to cause a significant glucose spike; however, for a horse with uncontrolled IR, PSSM, or a laminitis history, feeding sugar cubes isn’t a risk worth taking. Skip the sugary treats, too, if your horse is overweight, especially if he has a cresty neck. After all, every calorie counts and calories from treats mean feeding fewer calories from “real” food. Human research shows that tissues in insulin resistant people are more sensitive to insulin after exercise. This may or may not be the case in horses, but if it is, then your horse might be better able to handle the sugar in these treats when they are given shortly after work.

For the otherwise healthy horse, consuming a candy cane or a few peppermint candies is unlikely to have any major impact.

Researchers know that one of the best ways to reduce your horse’s risk of gastric ulcers is by providing him with consistent access to a high-quality forage. However, overweight horses might need a reduced amount of forage to facilitate healthy weight loss. Patty Graham-Thiers, PhD, of Emory and Henry University, in Emory, Virgina, describes the best ways to help an ulcer-prone horse lose weight.

This podcast is an excerpt of our Ask TheHorse Live Q&A, “Managing Your Horse’s Weight Through Thick and Thin.” Listen to the full recording here.

About the Expert

Patty Graham-Thiers, PhD

Patty Graham-Thiers, PhD, has 30 years of experience in higher education equine studies programs. She grew up in Massachusetts and received her BS in animal science from the University of Massachusetts at Amherst. She then earned her MS in equine nutrition from the University of Florida and PhD from Virginia Tech in equine nutrition and exercise physiology. She taught at Virginia Intermont College and currently teaches at Emory & Henry University in their Equine Studies Program. Her research focuses on protein and amino acid nutrition of exercising horses, and she also served on the National Academy of Science committee that published the 2007 Nutrient Requirements of Horses 6th edition.

The do’s and don’ts of feeding horses with 4 common health conditions

The sneezy, runny-nosed gelding in the barn sleeps on special dust-free bedding. A laminitic pony next door wears custom wedged shoes, and the ulcer-prone Thoroughbred across the aisle lives on a panoply of medications. Veterinary care, pharmaceuticals, and management play crucial roles when addressing disease. But we often overlook an equally powerful player: nutrition.

Many studies have proven a direct link between diet and disease in horses. Moreover, research shows many maladies have a nutritional component, meaning adjusting the diet can improve the condition. Here we’ll describe feeding practices that can help—or hinder—horses with four common diseases.

1. Gastric Ulcers

For decades scientists have known that stomach ulceration is prevalent in horses of all disciplines (McClure et al., 1999). Racehorses top that list, with up to 80-100% of those actively racing having gastric ulcers (Sykes et al., 2015). Even pleasure horses get ulcers—as many as 40-60% are affected. Luckily, we can adjust the diet to help. What to feed:

Free-choice forage Unlike humans, horses continuously secrete digestive enzymes and acidic juices in the stomach, including hydrochloric acid—a compound corrosive to eyes, skin, and mucous membranes. Horses have evolved to consume small amounts of fiber-based feeds around the clock, justifying this constant gastric fluid production. Offering free-choice forage helps prevent ulcers because fiber helps buffer the acidity. Otherwise, in the absence of feedstuffs to digest, gastric juices have nothing but the stomach lining itself to break down, leaving it inflamed, eroded, and ulcerated.

Alfalfa This and other legume hays are valuable sources of protein and calcium, making them particularly effective at buffering the stomach from its own acidic contents. Researchers have shown feeding alfalfa can help prevent and manage gastric ulcers (Lybbert, 2007).

Gastroprotective supplements Choose those backed by science, and offer them judiciously based on your vet’s advice.

What to avoid feeding:

Lots of concentrates Feeds high in nonstructural carbohydrates (NSC) increase volatile fatty acid (VFA) production. While VFAs are essential for fermenting fiber in the hindgut (the cecum and large colon), an abundance of VFAs in the foregut damages the stomach’s protective mucosal lining, leaving it prone to inflammation and ulceration (Nadeau et al., 2003).

Low-fiber diets The bulk of the equine diet should be forage; horses consuming < 1% of their body weight in forage daily are at increased risk of gastric ulcers.

Straw This grain crop byproduct has long been blamed for ulcers when fed in large amounts (Galinelli et al., 2019) or as the only forage source (Luthersson et al., 2009). But in a 2021 study researchers couldn’t correlate good-quality wheat straw as 50% of horses’ daily forage allowance with ulcer development. This suggests good-quality straw might be a suitable dietary component but should not replace hay or grass as forage sources.

2. Metabolic disorders

These include insulin dysregulation (ID), equine metabolic syndrome (EMS), and the hoof disease laminitis. Obesity is the top cause of metabolic dysregulation, so diet has the single biggest impact on prevention/management. What to feed:

Enough to meet nutritional requirements Don’t starve obese and laminitic horses out of fear that eating will kill them. If you restrict a horse’s feed intake too much, you could end up dealing with an array of secondary health problems: gastric ulcers, colic, nutritional deficiencies, weight loss, muscle wasting, and behavioral issues, to name a few.

Low-NSC forage Prioritize good-quality hay over grass, as fresh grass generally has high sugar levels. Depending on the severity of your horse’s metabolic dysregulation, your vet might recommend limiting grass intake or steering clear of it altogether. “If blood insulin concentrations are high, test the hay to ensure NSC levels are low enough that you can safely feed it to your metabolically challenged horse,” says Nicholas Frank, DVM, PhD, Dipl. ACVIM, a professor of large animal internal medicine at Tufts University’s Cummings School of Veterinary Medicine, in North Grafton, Massachusetts.

Soaked hay Soaking hay for 30 minutes (and tossing the water before feeding) reduces its sugar content. This simple practice can be an effective way to reduce NSC intake. “If you soak the hay for longer periods of time (two-plus hours), however, you are likely to leach vitamins and minerals out of the hay,” Frank cautions.

Ration balancer instead of concentrates If your horse doesn’t need extra calories from grain, you can complement his forage-based diet and meet his vitamin and mineral requirements by feeding a small amount (about 1-2 pounds daily, depending on body size) of a ration ­balancer. 

Frequent small meals If he does need concentrates to meet calorie needs, break his rations into small meals (< 1.1 gram/kilogram of body weight per meal) to avoid hyperinsulinemia, or high levels of insulin in the blood (Vervuert et al., 2009).

Fat for additional calories Unlike NSC, dietary fat is not associated with an increased risk of developing laminitis. Fat does not contribute to ID or EMS, either.

What to avoid feeding:

More calories than necessary, based on the National Research Council’s Nutrient Requirements of Horses. A calorie surplus can lead to obesity and fuels metabolic disorders. Overweight horses should operate at a caloric deficit to shed excess pounds. Consider all dietary components—forage, concentrates, and supplements—when calculating total daily caloric intake.

Lots of concentrates, because the starch and sugar rush translates to an insulin spike that can lead to ID. “The degree to which the diet needs to be managed depends upon the severity of ID and whether blood insulin concentrations decrease when initial management changes are made,” says Frank. “The severely affected animal with profound hyperinsulinemia has to be handled carefully, and all feeds must be low in NSC.”

Lots of sugar-rich treats Let’s not forget those peppermints—in abundance, they, too, can contribute to ID in at-risk horses.

What about horses with equine Cushing’s disease (pituitary pars intermedia dysfunction, PPID)? This is often, but not automatically, associated with ID.

“If he does not have ID, the horse with PPID can be fed like a regular senior citizen,” Frank says, noting that PPID horses tend to be older than 15. But the horse with both conditions needs a diet adapted first and foremost to ID. Therefore, when planning your PPID horse’s diet, Frank recommends starting by assessing his insulin status (via blood test) to determine whether he also suffers from ID.

3. Respiratory problems

Management and medication are the primary ways we manage equine respiratory conditions such as equine asthma, but certain dietary adjustments can also help horses breathe easier. What to feed:

Fresh grass, assuming your horse doesn’t have pasture-associated asthma. “One of the advantages of fresh pasture is it generally contains high levels of two important antioxidants: beta-­carotene (a vitamin A precursor) and vitamin E, which is known to prevent inflammation,” says Laurie Lawrence, PhD, professor of equine science and nutrition at the University of Kentucky, in Lexington.

Soaked or steamed hay to reduce dust and mold particles that irritate your horse’s airway mucosa.

What to avoid feeding:

Round bales, which are notorious for being dusty in the middle.

Hay directly on the ground, especially in a dirt lot, which increases your horse’s inhalation of dirt particles.

Pro-inflammatory ingredients “Diets that are high in some types of fat may be high in omega-6 fatty acids that are more pro-inflammatory than omega-3 fatty acids,” Lawrence says. Cereal grains such as corn and oats contain much higher levels of omega-6 than omega-3, a ratio conducive to inflammation. In a horse with inflamed airways, it’s vital to ensure the diet contains more antioxidants than pro-inflammatory agents, even though researchers haven’t yet confirmed ideal numbers and ratios, says Lawrence. “If the horse is consuming plenty of fresh grass and receiving concentrates, his antioxidant status is probably good,” she says. “However, if hay is his main forage source, adding a ration balancer fortified with trace minerals or a vitamin supplement that provides at 500 to 1,000 IU of vitamin E per day might be beneficial in terms of their antioxidant intake.”

4. Dental problems

Horses of any age can have difficulty chewing their food because of sharp, loose, or broken teeth. Here’s how to make mealtime easier for them. What to feed:

Soaked grain It’s easier to slurp soup than chomp hard feed.

Processed forage like hay cubes/pellets, instead of long-stemmed hay that requires extensive chewing. Soak before feeding.

What to avoid feeding:

Dry beet pulp To avoid choke, soak this highly digestible, easy-to-chew fiber source thoroughly. Choke can affect any horse fed insufficiently soaked beet pulp.

A grain-only diet Don’t skimp on forage because your horse struggles to chew hay. Again, turn to alternative forage sources. Complete feeds can also help horses that have trouble chewing long-stemmed fiber.

Take-Home Message

A holistic approach to disease management includes nutrition. Your veterinarian and nutritionist are well-informed when it comes to formulating a diet that can alleviate—or, at the very least, not aggravate—your horse’s particular condition. And for the healthy equid, provide a diet designed for long-term health.

Rather than repeatedly treating horses for equine gastric ulcer syndrome (EGUS) and spending a lot of money on medication, veterinarians and horse owners should focus on preventing the condition using better management practices. This was a key message from Ben Sykes, BVMS, MS, MBA, Dipl. ACVIM, PhD, FHEA, a veterinarian and gastrointestinal disease researcher based in New South Wales, Australia, during his presentation at the 2024 National Alliance of Equine Practitioners Convention, held Sept. 25-28 in Saratoga, New York.

“Anytime we discuss EGUS it’s important to appreciate that squamous and glandular disease are two completely different diseases,” said Sykes. A horse may have only one type of ulcer, or if they’re particularly unlucky, they can have both simultaneously.” Squamous ulcers occur in the upper third of the stomach while glandular ulcers form in the lower region.

Sykes highlighted three factors that remain crucial when preventing squamous disease:

1. Roughage: amount and timing;
2. Nonstructural carbohydrates: amount per meal; and
3. Exercise: amount and timing.

Optimizing Feed for Ulcer Prevention in Horses

“We want a nice, firm ball made of long-stem roughage (floating in the stomach’s gastric fluid),” said Sykes. “And we want this ball to have structural integrity as well as strong buffering capacity. The simplest way to get that is to offer free-choice hay and, in some cases, to tweak how we offer the feed to optimize the grazing period. The aim is about 1.5% dry matter per day, which is about 2% body weight on an as-fed basis.”

Sykes noted that study results on the protective effect of pasture in horses with a history of squamous disease vary dramatically. He suggested this could be because of pasture type. For example, in one study researchers showed that horses with pasture access were three times less likely to have squamous disease than stabled horses, but that was a dry pasture. Authors of other studies have, counterintuitively, demonstrated no protective effect of pasture turnout, especially on fields with high levels of nonstructural carbohydrates (NSCs) and soft, watery grasses.

“We don’t give our horses at risk of ulcers sweet feed, and pasture can be like sweet feed in terms of NSCs,” said Sykes. “In the stomach, some pastures with high NSCs can make sugar soup that is not protective like a ball of roughage. It may, in fact, increase the risk of squamous ulcers due to the contributions of fermenting NSCs damaging the mucosa.”

In terms of feed timing, Sykes said offering alfalfa hay before exercising the horse is most beneficial. This optimizes the roughage ball for protection before the highest risk period for damage to the squamous mucosa (i.e., exercise).

Monitoring a Horse’s NSC Intake

While the amount of NSC a horse eats contributes to squamous disease, Sykes suggested it’s probably an overstated risk factor for most riding horses.

“The majority of riding horses eating modern, well-formulated diets don’t eat enough NSCs for it to be a major driver of disease,” said Sykes. “It’s usually only the super-high performance horses or those without well-formulated diets. For most horses we need to worry less about this and focus more on roughage.”

Still, horses should not consume more than 1 gram of NSC/kilogram (of body weight)/meal, and ideally you should aim to feed less than 0.5 g NSC/kg/meal.

Adding beet pulp to the diet might also be useful. “Feeding beet pulp reduced the risk of squamous ulcers fivefold in one study,” said Sykes. “This is a cheap and easy management change with apparent benefits.”

Reducing the Horse’s Exercise Duration

“During exercise, horses contract their abdominal muscles, effectively lifting the acid level onto the area of the squamous mucosa,” said Sykes. “It’s the durationof exercise at the trot or above, not intensity, that is the primary driver for squamous ulcer risk. As a recommendation, aim for an average of less than 30 to 40 minutes per day. That’s still quite a lot.”

As a solution, Sykes recommended a faster cooldown, noting that the sooner the horse slows to a walk, the sooner the acid in the stomach settles to its normal location.

Ideally, riders should not exercise their horses first thing in the morning when no ball of forage exists in the stomach to prevent stomach acid splashing. Instead, it’s preferable to exercise after the horse has spent some time grazing or eating hay to reinforce its roughage ball.

If you must exercise in the morning, do it after the horse has eaten a significant roughage-based meal.

“This meal should include hay, not short-stem substitutes like cubes and pellets,” said Sykes. “Cubes and pellets form soup, not a roughage ball, and soup doesn’t stop acid from splashing around. Horses also chew two to three times less when eating cubes and pellets than when eating hay. Less chewing equals less saliva, leading to less natural buffering. This, in effect, gives a double negative of less buffering and no roughage ball, leaving acidic stomach contents free to splash around despite alfalfa’s modest direct buffering capacity.”

He added that alfalfa makes the ideal hay for horses with squamous ulcers, but grass hay serves as a sufficient alternative when alfalfa is unavailable.

Managing Horses That Have Glandular Disease

Sykes noted that the list of actionable steps for preventing glandular ulcers is much shorter, simply because researchers don’t know as much about this disease as squamous.

“It’s a stress-based disease, so our focus is on behavioral aspects of management,” he said. “Diet has not been shown to be a causative factor for glandular ulcers, but it might be a therapeutic target. Some studies have shown that glandular ulcers can be improved by reducing carbohydrates and including alfalfa hay. And there may also be some benefit in adding oils, specifically marine-derived omega-3s.”

Sykes said in his opinion, the No. 1 way to prevent glandular ulcers is to provide sufficient rest days. He recommended scheduling two to three days of rest per week and removing confounding stressors such as orthopedic disease, poor saddle fit, and other causes of chronic pain.

“If glandular disease is a disease of stress, then it makes sense that other causes of pain can contribute to glandular disease,” Sykes said.

Additional research-supported ways of preventing glandular disease include minimizing handlers and trainers, offering a regular routine, massaging or grooming the horse, and playing relaxing music.

“Enriching the horse’s environment should help prevent glandular ulcers,” said Sykes. “Every horse needs a friend to groom and cuddle, and the worst thing we’ve done for horses is take a herd animal and make it live in isolation. Some European countries are legislating that horses must have an equid companion, which is a great step forward.”

Take-Home Message

“By focusing on these items, we theoretically should be able to manage squamous ulcers out of most riding horse populations,” said Sykes.

He did point out to practitioners that it’s hard to offer everything to every owner. “To be successful, we need to pick what each owner can do, but we can make an important difference with relatively simple interventions.”

“They’re not lame, they’re just not…right.” 

I commonly hear this as many horses present to our practice for vague signs of poor performance or even behavioral issues. Trainers often will say that the horse is misbehaving and they want to make sure there is not a physical issue before assuming it is a training issue. In my experience, it is very uncommon for a horse to misbehave for no reason and behavioral issues under saddle are usually indicative of an underlying physical problem. Thus, our job as veterinarians (and owners and trainers) is to find the problem and help the owner and/or trainer develop a plan to move forward. While this can sometimes be a challenging and exhaustive process, it is ultimately rewarding if the underlying physical cause can be identified and resolved. 

Although there is an almost endless list of things that can cause poor performance and/or behavioral issues under saddle, orthopedic and musculoskeletal disorders are a common culprit. This underscores the importance of a thorough history, physical examination and lameness examination when working up these cases. In more straightforward cases, the horse may present with a visible lameness, therefore the first step is to block and regionalize the lameness. It is important to keep in mind that the site of lameness may or may not be related to the presenting complaint. Re-evaluating the horse under saddle after the lameness has been blocked can clarify if the lameness is the source of the behavioral issue or not. 

Conversely, there are multiple orthopedic conditions that can manifest as performance issues rather than lameness, including axial skeletal pain (pain of the neck, thoracolumbar spine and/or pelvis), front foot pain and hind proximal suspensory pain. Therefore, in horses without overt lameness, it can be enlightening to block the front feet and/or hind suspensory ligaments to see if it subsequently changes the behavior under saddle. For evaluation of the axial skeleton, sometimes blocking is also employed. For example, in horses with kissing spine, the horse can be evaluated under saddle before and after blocking the affected sites to assess the extent to which the kissing spine is a contributing factor. Most veterinarians are less comfortable blocking the neck or SI region and, therefore, if involvement of these regions is suspected, many veterinarians rely on imaging and trial treatment of those regions. Response to treatment is then used to help determine if these regions are playing a role in the performance issues. 

Looking beyond orthopedic causes, there are multiple muscle diseases that characteristically present with vague signs of poor performance, including stiffness, unwillingness to go forward, inconsistency in the contact, lack of impulsion and loss of quality of gaits. Particularly in Warmbloods, muscle diseases such as myofibrillar myopathy (MFM) and polysaccharide storage myopathy (PSSM) should be on the differential list. In several breeds, including Quarter Horses, Paints, Appaloosas, Belgians and Percherons, many muscle diseases can be diagnosed with genetic and/or blood testing. However, in Warmbloods, a muscle biopsy is almost always necessary to confirm a diagnosis. 

Respiratory disease, including disorders of the upper or lower airway, is another common cause of performance issues and often presents as exercise intolerance. Obstructive conditions of the upper airway such as pharyngeal collapse, dorsal displacement of the soft palate and laryngeal hemiplegia can understandably lead to exercise intolerance. The most common lower airway diseases include equine asthma and exercise induced pulmonary hemorrhage (EIPH/ Bleeders). A bronchoalveolar lavage and dynamic endoscopy can help to rule in or out most of these respiratory conditions. The cardiopulmonary system should also be evaluated in cases that present for exercise intolerance, as certain cardiac arrhythmias and murmurs can, unsurprisingly, lead to performance issues. 

While gastric ulcers can cause behavioral issues, they seem to get blamed for behavioral issues at a disproportionate rate. Although gastroscopy (a video camera inserted into the stomach) is the gold standard to diagnose gastric ulcers, riding the horse following “blocking” the stomach with lidocaine or following a dose of sucralfate can potentially help determine if gastric ulcers are contributing to the horse’s clinical signs. 

Hormones should also be mentioned when discussing potential sources of performance and behavioral issues, particularly in mares. Oral altrenogest can sometimes be helpful to assess and/or mitigate hormonal influence. Interestingly, there are mares who continue to show behavioral issues while on altrenogest that improve dramatically following ovariectomy, causing some owners to consider this in non-breeding stock. 

In summary, there are an exhaustive number of things that can lead to performance issues in horses. A thorough history and examination, in addition to the above investigations, will often lead to an answer in the many of these cases. It is important to keep in mind that most behavioral issues are not behavioral at all but rather a manifestation of an underlying physical problem. Keeping this in mind helps us approach these cases with empathy and an open mind. 

Editor’s note: This is an excerpt from Equine Disease Quarterly, Vol. 33, Issue 4, funded by underwriters at Lloyd’s, London, brokers, and their Kentucky agents. It was written by Erin K Contino, DVM, MS, Dipl. ACVSMR, associate professor of equine sports medicine and rehabilitation, at Colorado State University’s College of Veterinary Medicine and Biomedical Sciences, in Fort Collins.  

Equine gastric ulcer syndrome (EGUS) causes significant discomfort for horses across all breeds and disciplines. Preventing this disease plays a vital role in improving equine welfare and performance. The umbrella term EGUS covers two types of equine gastric ulcer diseases: glandular and squamous. “This distinction is based upon the location and underlying cause of these ulcers,” says Nimet Browne, DVM, MPH, Dipl. ACVIM, associate veterinarian in the department of internal medicine at Hagyard Equine Medical Institute, in Lexington, Kentucky.

Types of Equine Gastric Ulcers

Squamous ulcers, occurring in the top third of the stomach, are more common in many equine populations, such as racehorses and often attributed to excess exposure to stomach acid. “This is a management-focused disease, primarily associated with three key factors: the amount and timing of roughage, the amount of carbohydrates, and the amount and timing of exercise,” says Ben Sykes, DVM, BSc, BVMS, MS, MBA, Dipl. ACVIM, PhD, FHEA, a veterinarian and gastrointestinal disease researcher based in New South Wales, Australia.

Researchers are still working to better understand glandular ulcers, which affect the lower region of the stomach. “Risk factors for this disease are a little vaguer and, so far, a true nutritional component has not been identified,” says Browne.

“Regarding glandular disease, stress plays a much bigger role as does the horse’s individual susceptibility and the number of exercise days per week, rather than exercise quantity,” adds Sykes.

Diagnosing and Treating EGUS in Horses

If you believe your horse might have gastric ulcers, contact your veterinarian to diagnose the issue and develop a treatment and management plan. “Gastroscopy can be performed under minimal sedation and even in some cases at the farm,” says Browne. “It does involve at least eight to 12 hours of fasting to ensure an empty stomach. By using gastroscopy to identify the presence of disease, an appropriate treatment plan can be determined.”

Most horses with squamous disease return to normal with omeprazole treatment alone, she says, while only 25% of horses with glandular ulcers respond to this treatment approach. “Therefore, knowing the type of ulcers a horse has can help provide the most appropriate treatment that is tailored specifically for the individual horse,” she adds.

Understanding the differences between the two diseases can help owners and veterinarians focus their efforts where they can be most impactful. “Because squamous has a lot to do with diet, we naturally focus heavily on that for its prevention,” says Sykes. “In contrast, diet plays a much smaller, if any, role in glandular disease, so our strategies for prevention must reflect this. If we only focus on one side of the coin, then we don’t set the horse up for success in terms of total gastric health.”

A Holistic Approach to EGUS Prevention in Horses

A horse’s health and performance history, environment, and diet all contribute to his risk of developing gastric ulcers. “We must consider all these factors when designing an ulcer prevention program,” says Sykes. “This loops back to why knowing the difference between diseases and which one affects your horse—you can’t treat or prevent what you don’t know about.”

Work with your veterinarian to identify the underlying causes of stress or pain that might contribute to your horse’s gastric health “After diagnosing and treating ulcers, if progress seems halted, it is important to consider a holistic approach,” says Browne. “Performing a full orthopedic examination to identify musculoskeletal causes of pain, ensuring that the remainder of the gastrointestinal tract is healthy by addressing nutritional issues and considering herd health dynamics, is usually a good place to start.”

Keep in mind that this treatment journey might take time; each horse is unique and responds differently to treatment approaches, so you and your veterinarian might adjust your horse’s plan as needed.

Management Changes to Prevent EGUS in Horses

“Management changes continue to be the hallmark of therapy for both treatment and prevention of gastric ulcers in horses,” says Browne. Important management considerations for the prevention of squamous ulcers include forage types and availability, carbohydrate load, and exercise.

For horses with a history of squamous ulcers, the amount and timing of their forage intake is crucial. “We want our horses to ideally have unrestricted access to good-quality roughage, typically grass hay, at all times, supplemented with long-stemmed (i.e., hay, not chaff, pellets or cubes) alfalfa before exercise, says Sykes. “Where it is not possible to have unrestricted access to roughage, we want to make sure that we are feeding frequently and encouraging steady, slow consumption using strategies such as slow-feeder hay nets.”

A horse’s carbohydrate intake can also affect their risk of developing squamous ulcers. However, many recreational riding horses do not eat enough carbohydrates to significantly increase their risk, says Sykes. “Lastly, it’s exercise, specifically in the context of how much exercise at a trot or above in any given period (the ideal is five days or less each week) and timing,” he explains, with afternoon exercise preferred in most cases because this is when horses tend to naturally have the most hay in the stomach and, thus, the most natural protection.

For horses with a history of glandular ulcers, rather than focusing on total amount of exercise, owners should be attentive to the number of rest days their horse has (at least two per week is ideal) and environmental factors that could affect their stress levels. “This includes factors such as ensuring cohabitation and the opportunity to groom other horses, as well as managing human-related factors such as reducing the number of handlers or riders in sensitive horses,” says Sykes. “Behavioral modification is also important for glandular disease to reset the relationship that chronically affected horses form with the activities that we are asking of them (e.g., riding) and any pain that they might have historically experienced during such activities.”

Nutraceuticals for Preventing EGUS in Horses

“When management changes along are not sufficient, we shift towards using specific evidence-based supplements to reduce disease risk and chronic disease’s impact,” says Sykes.

A variety of nutraceutical products on the market are designed to support gastrointestinal function, but owners should be sure to choose only those with scientific backing. “Fatty acids, especially long-chain fatty acids found in fish oil (n-3 LC-PUFAs) have been shown to decrease inflammation and, in recent studies, did show a potential beneficial effect when compared to fatty acids derived from corn or flax,” says Browne. “Therefore selecting a nutraceutical derived from fish oil primarily over those with corn or flax might be beneficial.

“Pectin, which is gel-like coating agent, and lecithin, which is a phospholipid, both coat and provide a barrier against stomach acid to protect the mucosa,” she continues. Researchers have shown that licorice, aloe vera, and hyaluronan might be beneficial for preventing gastric ulcers, but more research is needed on the efficacy of these products, she adds.

Pharmaceuticals for EGUS Prevention in Horses

Veterinarians can incorporate long-term pharmaceutical management into EGUS prevention strategies at their discretion. There are many studies in which researchers have evaluated the long-term use of omeprazole along with other preventative strategies, says Browne. “The data suggests that pulse therapy in times of stress, rather than long-term use of low doses of omeprazole, would be the best usage of this medication,” she adds. However, only implement this strategy at the direction of your veterinarian and in conjunction with other long-term management strategies.

Take-Home Message

Equine gastric ulcer syndrome has a variety of risk factors associated with its development and recurrence. Therefore, taking a holistic approach to curating a prevention strategy can improve its likelihood of success. Work with your veterinarian and consider your horse’s history, environment, exercise program, and diet when developing a gastric ulcer prevention and management plan.

Q. I compete with my horse in the jumpers year-round. I know that it is advisable to feed a small meal before riding to prevent ulcers, but what is the best practice for showing? Should I feed my horse a small meal before he shows? If so, how far in advance and what would be best to feed him (forage vs. concentrate, etc.)?

A. It is great that you are thinking about preventing ulcers, or at least decreasing their severity, before they start.  Studies have shown that 60 to 90 percent of performance horses have ulcers. Unfortunately, typical show horse management practices, including stall confinement, higher-concentrate (grain) diets, travel to new venues, and stress level, can contribute to ulcer development. Horses that develop ulcers often exhibit nervous or aggressive behaviors, sensitivity in the back or girth area, teeth grinding, decreased appetite and poor performance. They might also lie on their backs in their stall, which seems to alleviate some of the pain associated with gastric ulcers. 

Gastric ulcers occur when acids produced in the stomach, such as hydrochloric acid, come in contact with the wall of the upper stomach (called the squamous region). This region does not have a protective mucus layer, like what is found in the lower, glandular region, which is where acids are secreted. In performance horses this often happens during exercise. Feeding practices, such as infrequent meals, can leave the stomach empty; however, horses are designed to eat small, frequent meals and secrete acid constantly. An “empty” stomach, which occurs when meals are quickly digested and separated by several hours, is more susceptible to developing ulcers. 

There are several things you can do, from a dietary standpoint, to help lessen the incidence of ulcers at shows and at home. If you are feeding a concentrate, divide it into multiple small meals throughout the day to decrease stomach acidity (more on why this helps in a moment). You could also switch to a feed higher in fat, which can help to decrease stomach acidity. Your horse should have access to high-quality forage throughout the day, and hay containing a legume, such as alfalfa, will be higher in calcium, which is a natural buffer for stomach acid. From a management standpoint you should hand-walk and hand-graze your horse—or even give your horse some turnout in a paddock, if available—to help decrease your horse’s stress levels, and provide him with more forage. 

You are correct that feeding a small meal prior to competing can help prevent ulcers. However, you need to be careful regarding what you feed. A grain meal is not advisable, but owners should avoid filling the stomach with a large hay meal. A good alternative is to feed about a pound of chopped forage 30 minutes prior to competing. This will provide a few advantages: it will fill the stomach so it is not completely empty, and the forage will also essentially form a cover which will float on top of the acidic fluids and can keep the acid from splashing on the squamous region.  

If you have any concerns that your horse has ulcers developing, consult your veterinarian. There are medications containing omeprazole and some natural supplements that can help heal the ulcers, and most horses respond positively with improved attitude and better performance. You should also speak with a nutritionist to make sure you are meeting your horse’s dietary needs and minimizing the potential for ulcer development. 

5 health conditions you and your vet should watch for when you’re trying a horse to buy

In early spring 2022 Carly Ostrander signed an agreement to take a young Quarter Horse mare on trial before deciding whether to buy her. Ostrander paid half the mid-five-figure asking price for a 60-day test ride. She hoped the horse would become her next mount for national-level ranch and reined cow horse events and, later, a broodmare.

Ostrander rode the mare in a two-day clinic preceding her first show. The mare was working cattle well despite having had a few years off. Hours before their first class, the mare tied up.

Fortunately, a veterinarian and an ­ambulatory technician show on the same circuit. They ran intravenous fluids; the mare responded to treatment and was cleared to compete. However, the vet suggested following up with a polysaccharide storage myopathy (PSSM) test. In PSSM cases a mutation of the GYS1 gene causes muscle cramping due to abnormal glycogen (sugar) storage in the muscles.

“At that time, they told me that even if it was PSSM, it could be managed through diet and exercise,” Ostrander says.

After the show she ordered a barrage of bloodwork and sent a hair sample to the University of California, Davis, Genetics Laboratory. The results confirmed PSSM. Believing the situation was manageable, Ostrander and the seller, who had never noticed the mare tying up in the past, negotiated a reduced price. Ostrander kept the mare even though she didn’t have a future as a broodmare (PSSM is hereditary).

Following veterinarian recommendations, Ostrander continued competing and attended the American Ranch Horse Association (ARHA) World Show in Ocala, Florida. It was a 25-hour drive from her upstate New York barn, and she opted for layovers to make the trip easier on the mare. A few days into the show, however, the mare had a severe tying-up episode.

“Here we went with more fluid, more drugs, more bloodwork, and lots of bills,” she says. “I learned that sudden bursts of motion and standing in a stall for long periods of time can trigger an episode. Essentially, this horse is not well-suited to be a reiner or a cutter and is better suited to be a trail horse or a pleasure horse.”

Getting any horse, especially of this caliber, on lengthy trial is typically uncommon, says Beau Whitaker, DVM, CERP, co-owner at Brazos Valley Equine Hospital, in Salado, Texas. Allowing a horse to go home with a potential buyer can pose risks, so many sellers will not agree to a trial. However, if you are permitted to take a horse on trial—and even a weeklong trial can be advantageous—he recommends watching closely for signs of injury or illness.

A prepurchase exam and results from genetic testing (when available) reduces the guesswork when identifying a horse’s potential health issues. Trials offer an extended time to observe any medical conditions not previously visible and consult your veterinarian about them. The results could make or break the deal.

If you arrange for a trial, Whitaker suggests looking out for signs of these five health conditions.

1. Lameness

Soundness is the most common health characteristic buyers look for, Whitaker says. Lameness can be the result of an injury or wear and tear and can require ongoing maintenance, such as joint injections.

“Buyers need to consider how much maintenance they can live with, as it will increase ownership costs,” says Whitaker. “In addition, severe injuries could mean the horse is unusable for an extended period.”

He suggests observing the horse on a longe line and under saddle for:

• Head bobbing when trotting.
• Gait unevenness.
• A limb creating a “dropping out” appearance (or sensation, when riding) mid-stride.

Soundness issues are not limited to legs and joints. Problems in the axial skeleton, which includes the skull, vertebral column, sternum, and ribs, can also create lameness. Whitaker says neck pathology (disease or damage), kissing spines, or sacroiliac joint (SI) issues can also be performance-limiting.

“Stiffness in the neck or back and soreness in these areas after work suggests there may be an underlying issue,” he adds.

2. Hoof Problems

Hoof issues often get lumped under lameness, but it is essential to consider the foot on its own, says Whitaker. Corrective shoeing increases the expense of ownership and, depending on discipline and work intensity, the pathology at hand can limit performance.

Cornell University’s head of farrier service, Steve Kraus, CJF, has fielded many calls from clients who discovered unsoundness after buying a horse without a prepurchase exam, with laminitis, ringbone, navicular disease, and hock osteoarthritis being the most common discoveries.

If you have a horse on trial, Kraus suggests the veterinarian and farrier:

• Walk and trot the horse on hard ground to watch for head-nodding or hip-hiking.
• Watch to see if the front feet are landing toe first and, if so, search for the underlying problem.
• Examine the hooves. Farriers look for fever rings and abnormal growth patterns, which might indicate chronic laminitis.
• Evaluate hoof size. Farriers are good at evaluating hoof size relative to body size. “Inappropriately small feet usually lead to lameness,” he says.

Kraus describes a situation in which a regular client bought a competitive horse. When he arrived for the first shoeing, he immediately noticed mismatched front feet and asked if anyone evaluated the horse prior to purchasing. The client responded that the veterinarian conducting the PPE commented about the horse having a small foot and said, “I hope you have a good farrier.”

“I shod the horse to compensate for unevenness, and he moved well, but I predicted that the horse would not stay sound with increased work,” he says. “Eventually the horse became too lame to continue training.”

Whitaker adds that if you notice the horse is shod with anything other than normal shoes or has pads or a wedge, it is important to ask for details before buying.

Even when looking at feet, don’t forget to step back and consider faults in the horse’s overall conformation. “A high/low front end, a base-narrow hind end, a butt-high build in mature horses, and cannon bones misaligned to the radius (forearm) are all conformation faults that can interfere with performance,” says Kraus.

3. Gastrointestinal Issues

Gastric ulcers require intense medical management, involving long treatment periods of expensive medication and ongoing preventive strategies. The prevalence of gastric ulcers can be upward of 90% in certain disciplines such as racing. It is important to recognize the signs, so you can not only alert your vet and initiate early treatment but also decide whether you’re up for the potential ongoing expense and management if you purchase the horse.

“Symptoms are wide-ranging but can include irritability when the girth is tightened or reluctance to move forward at a trot or canter,” Whitaker explains.

A horse that colics during a trial can also be cause for concern. Depending on the severity, it might even necessitate surgery. The specific case and prognosis can determine the horse’s suitability for the rider’s goals.

4. Respiratory Issues

Equine asthma syndrome is the most common respiratory issue Whitaker treats in performance horses. It can be ­performance-limiting and requires environmental management and ongoing medications. Environmental dust and molds are typically the causative agents, though a summer pasture-associated condition can affect some horses as well.

Management involves minimizing environmental dust from hay, grain, and other sources in and around barns. Horses with summer pasture-associated symptoms must be kept off pasture for part of the year. Due to the seasonality of the condition, they might seem perfectly fine during parts of the year and severely affected during others.

“Symptoms to look for (with both asthma types) are coughing, increased breathing effort relative to the amount of work, and taking longer than expected to recover after exercise,” Whitaker says. Exercise-induced pulmonary hemorrhage “is common in speed event athletes and should be factored into the decision if the horse has a history.”

5. Eye/Vision Issues

Eye issues are quite common on sale exams or whenever horses change hands, but they often go undetected by owners and trainers unless the problem is very obvious. During trial, watch for spooking at noises, as well as cloudiness in or squinting/drainage from the eye, which might indicate corneal inflammation, equine recurrent uveitis, and other ocular diseases. However, recognize that observation on trial is no substitute for a veterinary exam.

What If You Notice an Issue?

For Ostrander, her mare’s medical issues meant she couldn’t compete or be bred.

“So, I will not take her to any big shows. I will not put her in that kind of a situation where she has to be in a stall for an extended time. At my house she lives outside just about all the time,” she says. “I had to promise to keep her or that if I sold her that it be to a home willing to keep up her care.”

Fortunately, not all medical issues that can emerge during a trial period are as substantial as the one Ostrander experienced. Whitaker says if a health condition arises during a trial, have a frank discussion with your veterinarian and ask yourself:

• Does the issue keep me from using the horse for my intended purpose?
• Do I have the budget to manage the issue?
• Does that leave room in my budget for unexpected events that can arise and cost more than expected?
• Do I have the time to deal with an issue that requires daily therapy or medications? “This may not be a problem if you are at a barn with full board, but there may be an extra expense to pay someone else to give the medication,” he says.

Hindsight Is 20/20

Looking back, Ostrander says she should have returned the mare after the first episode. She was attached to the horse, however, and made an emotional decision rather than an objective one.

Also, going into the deal, Ostrander knew she had time to make an educated decision and opted to bring the mare home without a prepurchase exam or genetic testing. Without that trial period, she would have done both first. She took two actions when the mare came to her barn that made a significant difference in the outcome. First, she purchased major medical and mortality insurance right away. Second, she stayed in immediate and constant communication with the seller.

“He knew exactly what we were going through, what we were treating her for, and the time, energy, and money we were putting into vets, testing, and treatments,” she says.

The silver lining for Ostrander was the seller was committed to ensuring the mare had a good home. He recently sold his breeding operation and had no place to keep the mare. In exchange for knowing the mare he had bred and raised had a place with proper care, he refunded Ostrander’s ­deposit—something not all sellers are in a position to do. Similarly, not all buyers are in a position to add another horse to their herd if the horse cannot perform its intended use. “I’ll be forever grateful to Morgan (O’Brien, DVM) and Karlene (Bushey, ambulatory assistant) for saving my mare’s life that day,” Ostrander says. “Just be cognizant that you’re not letting your desire for instant gratification of something to show or something to ride outweigh your senses.”

9 reasons your horse might not be performing as expected

Say your horse starts refusing to move off your leg, kicks out, and swaps his lead behind—when you’re able to pick up the canter at all, that is. Your first instinct might be to blame his training or dismiss these issues as bad behaviors. In reality, a horse having difficulty performing as expected could be in pain. From a welfare standpoint, it’s always preferable to investigate and rule out physical reasons for difficult behaviors before handing the reins to a trainer or behaviorist.

But where do you start? Here we’ll walk through a workup with two vets who specialize in identifying roots of poor performance.

Poor Horse Performance Defined

When a ridden horse’s athletic abilities fall short of the rider’s expectations, you’re dealing with poor performance. “The list of potential problems causing poor performance very much depends on what type of poor performance we are talking about,” says Erin Contino, MS, DVM, Dipl. ACVSMR, associate professor of Equine Sports Medicine and Rehabilitation at Colorado State University, in Fort Collins. “If we’re seeing issues with physically being able to perform an athletic job, then respiratory, cardiac, and muscle diseases would be highest on my list of possibilities. On the other hand, if we are dealing with behavioral issues under saddle, then axial (body) skeletal pain and gastric ulcers top that list.”

With this in mind, let’s dive into nine common causes of poor performance in horses and what it takes to get a diagnosis.

The No. 1 Culprit: Lameness

• Diagnostic approaches Practitioners use palpation, lameness exam, diagnostic regional anesthesia (nerve blocks), lameness locator technology, radiographs, ultrasound, computed tomography (CT) scan, MRI, and nuclear scintigraphy (bone scan).

• Possible causes Diagnosing equine lameness involves an almost limitless range of possibilities. “The most common causes are probably hind-limb proximal suspensory disease and generalized front foot pain,” Contino says, reflecting on her experience. A horse’s discipline and workload greatly influence his predisposition to different injuries. Looking at two popular disciplines, researchers have suggested that show jumpers and eventers are especially at risk of developing flexor tendon injuries, while dressage horses are overrepresented in hind-limb suspensory ligament desmitis cases¹.

My Horse Isn’t Lame But Isn’t Performing Well. Now What?

Say your horse is “off,” but a thorough lameness exam, including flexion tests and nerve blocks, didn’t provide any answers. What’s next? We delve into the myriad other problems that can cause poor performance, Contino says. This conversation opens the door to what can be a complex, but necessary, investigation.

This is where an internal medicine specialist like Laura Javsicas, VMD, Dipl. ACVIM, of Rhinebeck Equine, in New York, comes in. After your primary veterinarian has ruled out lameness as the cause of poor performance, you and your horse will likely be referred to an internal medicine specialist. “When evaluating a horse for poor performance, I always start with getting a thorough history to pinpoint exactly what problems the rider is experiencing,” Javsicas explains. “When the source of the issue is nebulous, this process can help to target the area(s) to focus on.”

Regardless of case history, Javsicas starts with a complete physical exam, including careful auscultation (listening) of the heart, a rebreathing exam to listen to the lungs (which causes the horse to take deeper, slower breaths, making lung sounds easier to hear), and a neurologic exam. The results of this preliminary evaluation dictate her next move and could point her in several different directions. The common ones include:

2. Back Pain

Diagnostic approaches

Practitioners use palpation, radiographs to check for overriding dorsal spinous processes (kissing spines) and arthritis. Some veterinarians also start a horse on a 14-day course of the muscle relaxant methocarbamol (Robaxin) and see if the horse’s back pain improves. Some complex, idiopathic (occurring unexpectedly or from an unclear origin), and/or persistent back pain cases might warrant a visit to a board-certified sports-medicine specialist for further diagnostics, including advanced imaging.

Possible Causes

Horse owners commonly observe back pain in poorly performing athletes and veterinarians frequently identify it as a clinical issue. In 2011² study renowned equine sports medicine and rehabilitation specialist Kevin Haussler, DVM, DC, PhD, Dipl. ACVSMR, estimated that up to 94% of ridden horses experience some degree of back pain. There are likely several factors to blame for this statistic. A 2023 survey-based study revealed the single most diagnosed pathological cause of primary equine back pain is kissing spines², while other studies have identified ill-fitting saddles, among other riding-associated factors, as a common cause of equine back pain³. “While axial skeletal issues (including back pain) can cause lameness, they often present only as poor performance,” says Contino. “Axial skeletal pain, dysfunction, and/or pathology are the most common causes of poor performance in the horses that present to me.”

3. Muscular Disease or Injury

Diagnostic approaches

Veterinarians use serology, which involves testing blood levels of the muscle enzymes aspartate aminotransferase (AST) and creatine kinase (CK), both baseline and after an exercise challenge; genetic panel; and muscle biopsy. Javsicas also recommends performing genetic testing and having a muscle biopsy sample evaluated by an experienced veterinary pathologist.

Possible Causes

Hyperkalemic periodic paralysis (HYPP) and polysaccharide storage myopathy (PSSM) are genetic diseases that affect horses’ muscles. In Warmblood breeds myofibrillar myopathy (MFM) leads to muscular disease. PSSM and MFM most commonly cause clinical signs of tying-up and/or signs of vague poor performance, muscle soreness, and sometimes hind-limb gait abnormalities (depending on breed), while HYPP can cause muscle tremors and paralysis.

4. Neurologic Deficits

Diagnostic approaches

Veterinarians use physical, lameness, blood tests, and neurologic exams. They refer to an internal medicine specialist or neurologist for cerebrospinal fluid analysis (looking for pathogens that cause neurologic disease), CT scan, and myelogram (radiographs obtained under general anesthesia using a contrast injection around the spinal cord to look for compression). “Neurologic and muscle diseases can cause poor performance and are often confused with lameness,” notes Javsicas.

Possible causes

Equine protozoal myelocephalitis (EPM) stands out as the most common neurologic disorder in horses and is arguably overdiagnosed and overtreated. A 2017 study showed 78% of apparently healthy horses in the U.S. tested positive for EPM antibodies⁴, meaning they were exposed to but not necessarily actively infected with EPM. However, EPM can cause neurologic deficits that negatively affect a horse’s performance. Other neurologic conditions, such as equine degenerative myeloencephalitis (EDM), cervical vertebral stenotic myelopathy (CVSM), and Lyme disease can produce similar neurologic deficits.

5. Hoof Problems

Diagnostic approaches

Practitioners use lameness exams, hoof balance radiographs (lateromedial and dorsopalmar ), MRI, hoof testers, and diagnostic nerve blocks, and they might refer to a podiatrist.

Possible causes

Most foot problems stem from various musculoskeletal issues, primarily categorized as lameness (see No. 1). Researchers have shown hoof bruising and podotrochlosis (aka navicular syndrome) are the main foot-related causes of lameness and poor performance in both dressage horses and show jumpers⁷. Primary issues of the hoof capsule can also limit performance and include white line disease, solar abscesses and bruising, and hoof cracks, to name a few.

6. Respiratory Problems

Diagnostic approaches

Vets use auscultation, rebreathing exams, bronchoalveolar lavage (BAL), transtracheal wash (TTW), chest radiographs, lung ultrasound, and airway endoscopy to investigate these issues. Dynamic endoscopy has helped as a means of finding problems only present during work.

Possible causes

Javsicas cites equine asthma as one of the top three causes of poor performance she diagnoses. Otherwise, respiratory problems include everything from laryngeal hemiplegia (roaring) and dorsal displacement of the soft palate to epiglottic entrapment and arytenoid chondritis. Contino agrees, adding that the literature suggests upper airway conditions such as these are another common cause of poor performance in horses.

7. Cardiovascular Restrictions

Diagnostic approaches

Veterinarians use cardiac auscultation, exercise tolerance tests, electrocardiogram (ECG/EKG), and cardiac ultrasound.

Possible Causes

Heart problems also made the top-three list of causes of poor performance in Javsicas’ caseload, but this statistic likely does not represent the entire equine population. “Cardiac issues are a relatively rare cause of poor performance, but horses are referred to me—an internal medicine specialist—for further cardiac workup if a murmur is auscultated or arrhythmia detected, hence the bias,” she explains. Cardiovascular malfunction is, however, the most common reason for sudden death in horses during and immediately after exercise, says Cris Navas, LV, PhD, Dipl. ACVIM, a large animal internist at the University of Pennsylvania’s New Bolton Center Veterinary Hospital, in Kennett Square. In his presentation at the 2023 Veterinary Meeting and Expo (VMX) in Orlando, Florida, Navas cited atrial fibrillation as the No. 1 cause of cardiac limitation to horses’ athletic performance.⁸

8. Gastric Ulcers

Diagnostic approaches

“Gastric ulcers have a variety of clinical signs, including colic signs after eating, bruxism (teeth grinding), and girthiness,” Javsicas says. “Gastric ulcers can also cause poor performance. The most common manifestations I see are reluctance to move forward and bucking, signs that may mimic back pain. While these observations are helpful in guiding horse owners and veterinarians toward a gastric ulceration diagnosis, only a gastroscopy can confirm or rule out the presence of ulcers in an individual horse’s stomach and determine the location and severity of the ulcers, which dictates treatment.”

Possible Causes

Gastric ulcers are prevalent in many populations of equids, from racehorses and eventers to stabled horses in general. Risk factors include insufficient forage access, consuming grain on an empty stomach (not buffered by forage), high starch intake, and stress⁹. Javsicas says gastric ulceration is one of the most common culprits of poor performance she sees in her caseload.

9. Repro or Behavioral Challenges

Diagnostic approaches

Practitioners use serology to test for abnormal hormone levels in mares (estrogen and testosterone) and ultrasonography of the mare reproductive tract.

Possible causes

If a mare has a granulosa cell tumor on an ovary, the hormonal imbalance might cause her to display stallionlike behavior¹⁰. The neurologic disease EDM can also cause lethargy and aggression in horses of both sexes¹¹.

When Health Is Not the Problem

When dealing with a poorly performing horse, Contino reiterates first ruling out pain and lameness with a thorough clinical exam and the diagnostics listed above. “If my examinations don’t reveal anything obvious, depending on the case, I may recommend a Bute trial,” she says.

Much like the methocarbamol trial mentioned earlier, a Bute trial involves giving a horse the non-steroidal anti-inflammatory drug (NSAID) phenylbutazone daily for seven to 10 days. “The goal is to determine if the horse is any different on Bute—or not,” explains Contino. “If he improves, this indicates the performance issue does indeed have a pain or inflammation component.”

If Bute doesn’t ameliorate performance, Contino might recommend a gradually increasing fitness and conditioning program, depending on the case. She also adds physical therapy and gymnastics exercises and sees if the horse trends better—pointing to a fitness and conditioning issue. “If the horse gets worse during the fitness program, this suggests we are aggravating an underlying issue, and it’s back to the drawing board.”

Take-Home Message

“I do think horses with axial skeletal pain present more often for poor performance or behavioral issues than they do for lameness,” Contino says. “There isn’t a ‘one-size-fits-all approach’ to these complex poor performance cases. They can be tricky for sure!” Recognizing your horse is struggling and reaching out to your veterinarian is the best first step you can take to get to the bottom of the issue. It could take some time and trial and error, but trust your veterinary team will do everything possible to get you back in the saddle with a horse that’s feeling and performing his best.

References

1. Murray RC, Dyson SJ, Tranquille C, Adams, V. Association of type of sport and performance level with anatomical site of orthopaedic injury diagnosis. Equine Vet J. 2006;38:411–416.

2. Marshall-Gibson ME, Durham MG, Seabaugh KA, Moorman VJ, Ferris DJ. Survey of equine veterinarians regarding primary equine back pain in the United States. Front Vet Sci. 2023;Jul 26;10:1224605.

3. Greve L. and Dyson S. Saddle fit and management. Equine Vet J. 2015;47:415–421.

4. James KE, Smith WA, Conrad PA, Packham AE, Guerrero L, Ng M, Pusterla N. Seroprevalences of anti-Sarcocystis neurona and anti-Neospora hughesi antibodies among healthy equids in the United States. J Am Vet Med Assoc. 2017;Jun 1;250(11):1291–1301.

5. Mizumura K, Taguchi T. Delayed onset muscle soreness: Involvement of neurotrophic factors. J Physiol Sci. 2016;66:43–52.

6. Hotfiel T, Freiwald J, Hoppe MW, Lutter C, Forst R, Grim C, Bloch W, Hüttel M, Heiss R. Advances in Delayed-Onset Muscle Soreness (DOMS): Part I: Pathogenesis and Diagnostics. Sportverletz Sportschaden. 2018;Dec 32(4):243–250.

7. Dyson S. Lameness and poor performance in the sport horse: Dressage, show jumping and horse trials. J Equine Vet Sci. 2002;22(4):145–150.

8. Vigouroux L. Cardiac Limitations to Horses’ Athletic Performance. TheHorse.com. February 4, 2023. TheHorse.com/1121366.

9. Galinelli N, Wambacq W, Broeckx BJG, Hesta M. High intake of sugars and starch, low number of meals and low roughage intake are associated with Equine Gastric Ulcer Syndrome in a Belgian cohort. J Anim Physiol Anim Nutr. 2021;105(Suppl. 2):18–23.

10. Sherlock CE, Lott-Ellis K., Bergren A, Withers, JM, Fews D, Mair, TS. Granulosa cell tumours in the mare: A review of 52 cases. Equine Vet Educ. 2016;28:75–82.

11. Finno CJ, Johnson AL. Equine Neuroaxonal Dystrophy and Degenerative Myeloencephalopathy. Vet Clin North Am Equine Pract. 2022 Aug;38(2):213–224.

Q. My hard-keeping Thoroughbred does low-level eventing and is a picky eater, especially when he’s not working. Even though he has free-choice hay access, he only eats three to four flakes a day. Pasture in the summer helps, but now the pasture is gone for winter. He also won’t eat supplements … he sifts through or won’t eat any of his grain. How can I get calories into him?

—Lynn, Versailles, Kentucky

A. To start answering this question, it’s necessary to first visit why your horse is a picky eater. Some horses are simply picky eaters and hard-keepers, just like some people are! But others might have a reason that they don’t want to eat, and unlike people who have similar reasons, they can’t speak up and explain that to us.

Rule Out Health Problems

If a horse doesn’t have a good appetite, first and foremost a veterinarian should assess him for causes of a poor appetite. A proper oral examination might indicate your horse is overdue for a dental float, or he might have a tooth that’s causing him pain. Blood work could evaluate his organ function (especially that of his kidneys and liver) and rule out the possibility of an underlying infection. Examination by a veterinarian might also aid in determining whether your horse has gastric ulcers (via a gastroscopy) and requires empiric anti-ulcer therapy.

Trial and Error

Assuming your veterinarian has ruled out pathologic reasons for a poor appetite, then it’s possible your horse is simply a picky eater, and the goal becomes increasing his caloric intake. Consider offering different types of forage or grain to find something he finds palatable. Alternatively, consider adjusting his environment to determine if social hierarchy might be affecting his appetite (i.e., more aggressive horses are preventing him from eating).

Calculate the Calorie Deficit

If none of these strategies is successful, go back to basics and figure out how much the horse is actually eating.  This is necessary because it dictates how to proceed with adjusting his diet. A 1,000-pound horse who’s not in work needs approximately 15,000 calories per day to maintain his body weight. The daily caloric requirements of the same horse can increase to well over 20,000 calories per day when he’s in work. Different breeds of horses have different metabolic rates, so these numbers can vary quite a bit for individuals. However, it’s helpful to determine these needs and work backward from them.

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A pound of good-quality timothy hay contains about 800-1,000 calories. A pound of a complete pelleted feed contains about 1,000-1,200 calories. A horse should get most of his calories from these two types of feed, in addition to good-quality grass when possible and indicated. A pound of sweet feed contains about 1,500-1,700 calories. Sweet feed can be a helpful component of a horse’s diet, but it shouldn’t be a primary source of calories, because it ferments rapidly and can increase colonic gas production.

Once a horse’s average daily intake is determined, you can calculate his calorie deficit. If a deficit exists, you can make up the difference by incorporating a high-fat supplement into his diet. Several nutritional companies produce high-quality fat supplements that complement a horse’s diet well. These products often contain high-fat feeds such as rice bran and flaxseed, as well as vegetable oils. A pound of a high-fat supplement contains about 1,900-2,100 calories. It’s also possible to add rice bran or corn oil to feeds on their own, but many owners prefer products from a nutritional company, because these supplements are already neatly packaged, carefully formulated, and don’t require the extra mess or work. Introduce any high-fat supplement to a horse’s diet slowly and gradually, because a dramatic change in nutritional content can set the horse up for gastrointestinal upset and even diarrhea.

With these strategies, you can approach a horse’s finicky attitude toward feed more effectively. The feed recommendations I’ve provided are general, because hay quality can vary considerably and the composition of similar feeds offered by different companies can also differ significantly. Moreover, different breeds of horses have important nutritional considerations. Horses are much more reliant on the health of their gastrointestinal microbes than humans, so sudden changes to the diet can have serious consequences. I recommend consulting your veterinarian or equine nutritionist before making changes to your horse’s diet.

Q: I have a fair amount of experience feeding senior horses. At one point I had three of them on either hay pellets or hay cubes due to dentition issues that prevented them from eating long-stem hay. Because they could consume the cubes or pellets fairly quickly, there would be long stretches during the day and night where there was no forage for them to eat; at that point, they started chewing wood in the barn and on trees.

I currently have two seniors, one of which will chew on his buddy’s hay and spit out the quids, so chew time is not a problem.  Before, I had one gelding who would not only chew his hay but would then eat other horses’ quids, which resulted in mild impactions throughout in the last two years of his life.

My question is: What can I do to appease the need to chew for equids that can only eat hay pellets or cubes, chopped hay, or complete feeds because their teeth are no longer effective for chewing long-stem forage?  Would small-hole haynets allow them to just get a few pieces of hay at a time to chew on while reducing the risk of impactions caused by swallowing unchewed long-stem forage?

—Karen, via e-mail

A: Chew time is an important consideration not just because it gives your horse something to do and more closely resembles the horse’s natural feeding behaviors, but also because chewing results in saliva production. Saliva lubricates the feed being consumed, helps its passage down the esophagus, and contains a significant concentration of bicarbonate and calcium—both of which buffer stomach acid.

Horses in a natural setting spend the majority of the day foraging and chewing, and they constantly secrete stomach acid whether they are eating or not. The near-constant chewing and saliva secretion continually buffers the secreted acid. The highly fibrous plant matter being consumed also buffers stomach acid and forms a floating mat on the surface of the acid, preventing it from splashing around.

When the horse spends less time chewing—whether its due to reduced forage intake, the type of forage, or the method of forage provision—he produces less saliva and can’t buffer the stomach acid as well. This could increase a horse’s risk of developing gastric ulcers in addition to developing undesirable behaviors such as wood chewing, as you’ve described.

Meal-feeding restricted amounts of hay reduces total chewing compared to the amount of chewing that would occur if the horse was on pasture full time. Many horses will consume a flake or two of hay in less than a couple of hours, leaving long periods between meal times with no chewing. Slow feeders can increase the time spent chewing and, thus, producing saliva.

For horses with poor dentition, long-stem hay might no longer be a viable option because they cannot chew it adequately. Hopefully, this results in quids—balled-up mouthfuls of partially chewed hay that fall out of the horse’s mouth. I say “hopefully” because the other option is that the horse swallows the inadequately chewed hay and is at risk of impaction colic should the hay get stuck in the gastrointestinal tract. Of course, the major downside to quidding is that the horse gets no nutritional value from the hay when it’s not actually consumed.

Some senior horses appear to chew hay fine, but don’t maintain or gain weight with it as they have in the past. This could be because they’re no longer as effective at digesting hay as they used to be. Some of these senior horses might develop loose manure due to mild colitis caused by the hay irritating the colon. I have worked with several such horses, and all have improved in body condition and manure quality by consuming a diet made up either partially or completely of hay pellets.

Hay pellets or cubes are a good solution for horses with poor dentition and other horses that might require pelleted diets, such as those described previously or with equine asthma that need dust-free or low-dust feed. However, because the hay has been chopped up to a very fine size prior to being turned in to the pellet, it takes very little chewing to break the pellets into an easily swallowed size. This results in reduced chew time and saliva production. If your horse eats a flake or two of hay in only a couple of hours, the time it will take him to eat a similar weight of pellets will be substantially less.

For your horse that reliably spits out quids when chewing hay, you could continue to give him access to a small amount of hay; however, I suspect that the majority of the saliva being produced during chewing ends up in the quid and not in the stomach. Additionally, there is the risk that some of the hay is being consumed and increasing impaction colic risk, so I would discuss hay-feeding strategies with your veterinarian. Small-hole haynets might result in better overall chewing and fewer quids, so this might be a good option, as well, but again I would discuss this with your veterinarian who can fully assess your horse’s situation.

A better solution might be an automatic pellet feeder—essentially, a slow feeder for pellets. There are several versions on the market. Basically, you fill the feed hopper with your hay pellets and program the feeder to release a certain quantity at your preferred time. Most of these feeders sit outside the stall and direct the feed into a bucket in the stall by way of a funnel. Some feeders will drop all the feed you want at once—for example, you program it to feed all 6 pounds of pellets at 7 a.m. Other feeders let you program them to feed that same 6 pounds of feed in intervals—for instance, you can program it to feed approximately 48 2-ounce portions every 30 seconds or so. These feeders allow you to spread your pellet meals at intervals throughout the day to simulate grazing.

You can use these same feeders to provide concentrates to horses that can eat hay, spacing their pelleted or textured grain meals in small portions throughout the day. They are also a great way to supplement a hay-based diet with hay pellets. For example, maybe you want to program it to feed some pellets at 6 p.m. in case you get home from work late.

You can find a number of automatic pellet manufacturers by doing an online search using terms such as equine pellet feeder.

Hopefully using a solution such as an automatic feeder will keep your horses eating more consistently throughout the day and prevent them from looking for alternatives to chew such as your trees or barn!

Q: My 14-year-old Warmblood is in consistent upper-level dressage training, working hard three or four days a week in the arena and getting in an additional hack day per week on the trails. His coat doesn’t quite have the “bloom” I’d like it to (it’s a bit dull and course) and his topline isn’t quite as developed as I think it should be for his level of work. Is his topline possibly a nutrition rather than a training problem?

A: This is an issue I see fairly often in sport horses when out in the field doing farm calls. It can be a little difficult for some owners to put their finger on because at first glance it looks like perhaps the horse needs more weight, but when you assess the six areas of the body while performing a Hennecke body condition evaluation, you realize that actually the horse has enough fat cover over the ribs and often through the neck. The issue is that they lack topline muscling through the loin and sometimes in the saddle area and over the rump towards the tail. Adding more calories to the ration as you would for a horse that is truly underweight would likely just result in a fat horse.

The problem is less one of inadequate calories and more likely an issue of inadequate quality protein. It is very unusual for me to come across a ration with inadequate crude protein. Nearly all mature working horse’s rations are meeting their crude protein requirements, but in reality horses do not have a protein requirement they have an amino acid requirement. Amino acids are the units that make up proteins. Some of them are essential, meaning that they must be present in the diet, because the horse cannot make them itself. Others amino acids are non-essential, meaning that while they can be in the diet, the horse can actually make them too.

Amino acids are expensive to quantify in feed, and we don’t know exactly what the horse’s amino acid requirements are. The Nutrition Research Council does have an estimate for the amino acid lysine, but not for any other amino acids—the assumption being that as protein provides a broad range of amino acids, and amino acid requirements will be met if the crude protein requirement it met.

“Protein quality” is the protein proportion that’s made of essential amino acids. Therefore, a protein that provides a greater amount of essential amino acids is a higher quality protein than one that provides less. Most forages provide plenty of total protein for a mature horse in work; however, some forages provide a higher quality of protein than others. Protein quality might drop with maturity at cutting, and if indigestible fiber is high it might bind the protein, making it less available during digestion.

Legumes like alfalfa tend to have a better amino acid profile with more lysine than grass hays. Lysine is an essential amino acid that is often referred to as the limiting amino acid. A limiting amino acid is an essential amino acid that tends to limit protein synthesis because the amount of this amino acid in the diet is limited.

Protein synthesis is a process where RNA essentially calls out for specific amino acids and joins them together in a predetermined order that will result in the formation of a specific protein. It is a bit like making words in a sentence with the letters in the alphabet being amino acids with vowels being essential amino acids and consonants being non-essential amino acids and each word being a protein. If you were limited to having only three letter Es you would not be able to make many words. Once you had used up that third E the next time you needed an E and didn’t have one your word building would be over even though you might have lots of extra As and Ls etc. The same concept applies to protein synthesis. If you run out of lysine or any other essential amino acid your ability to create new protein is reduced until you consume more of the needed essential amino acid. This results in a less than optimal scenario for building proteins. Given that proteins are the basis of collagen, elastin, keratin, and muscle fibers, as well as hormones, enzymes, antibodies, etc., having adequate essential amino acids is crucial.

The fact that your horse has poor muscling over the topline as well as a dull coat could indicate the need for a source of higher quality protein in the diet. It is also important to remember that poor coat and lack of muscling can also be a symptom of gastric ulcers, so it’s always wise to have your horse looked at by a vet to rule out any underlying issues that might not be diet-related.

Another consideration for your veterinarian is the possibility of a vitamin E deficiency, as levels in hay are low and individual utilization of vitamin E varies by horse. A deficiency can be detected through blood work and could impact ability to develop good topline. Other issues that could prevent topline formation include conditions such as polysaccharide storage myopathy, joint or dental discomfort, problems with saddle fit, and shoeing errors.

Assuming the issue is protein quality, you need to add a source of better quality protein. Protein quality of pastures in spring and summer tends to be very good, so turnout is one option. However in winter, or if turnout would lead to undesirable weight gain, replacing up to a third of the horse’s current forage ration with alfalfa might help.

Another option is to utilize a high-protein ration balancing feed. These feeds tend to use soybean meal as a major protein source because it has the best amino acid profile of most of our plant-based feed ingredients. One ration balancer benefit is that it’s also highly fortified in trace minerals and important vitamins that can be lacking in your forage. The serving size is typically small—about 2 pounds per day for an average sized horse—and therefore doesn’t contribute a major source of calories. Most major feed manufacturers have a ration balancer—ask your feed store.

If you are already feeding a balanced diet with a source of additional vitamins and minerals, you might prefer to utilize an amino acid supplement rather than a ration balancer. Several such products exist on the market. Those that are beneficial to muscle development tend to provide amino acids from whey protein, which is highly bioavailable.

With improved protein quality in the diet and correct work I would expect you to see an improvement in overall topline development, as well as hair coat quality, in about four to six weeks.

Equine gastric ulcer syndrome (EGUS) poses a significant concern for performance horse owners, especially among racing populations. Omeprazole, the gold-standard treatment for equine squamous gastric disease (ESGD)—lesions in the upper part of the stomach—can be expensive and is available only by prescription. Given ESGD’s clinical and economic impact in racehorses, researchers have suggested an effective feed additive, such as magnesium oxide, could serve as a buffering option.

Manufacturers commonly include magnesium oxide in cattle supplements to control rumen pH. Researchers Claire Leleu, DV, PhD, founder of Equi-Test, and Anne Couroucé, DMV, PhD, Dipl. ECEIM, of Oniris-CISCO, both in France, evaluated the effects of magnesium oxide specifically on ESGD in 2-year-old French Trotters in active race training. They hypothesized that magnesium oxide-treated horses would have less severe ESGD ulcers than the controls.

Leleu and Couroucé split 42 horses into treatment and control groups, using a double-blinded, placebo-controlled study design. Two veterinarians performed gastroscopy on all horses on Day 0 and assigned an ESGD score from 0-4. In this system 0 meant an intact gastric mucosa; 1 referred to hyperkeratosis; 2, small single or small multifocal ulcers; 3, large single or large multifocal ulcers; and 4, extensive and/or coalescing ulcers with areas of deep ulceration. On Day 0 both the treatment and control groups had similar score distributions. Specifically, 30% of the horses received a score of 2, while 42.5% had scores of 3 or 4. These figures confirmed the high prevalence of ESGD in this population.

The research team fed custom pelleted feeds to the control and treatment groups, respectively, three times daily. The treatment version contained a blend of different sources of magnesium oxide, and it could not be distinguished from the control version. They initiated feeding the supplement 24 hours after initial gastroscopy and continued for 30 days, when veterinarians performed a second gastroscopy and scored all horses for ESGD again. Feed and training regimens remained consistent for all horses in the study to minimize confounding factors.

At Day 30 the researchers saw a significant decrease in the mean ESGD scores in the magnesium oxide group compared to the control group. This suggests the supplement was successful at increasing gastric pH and promoting healing of the gastric mucosa. The researchers also looked at oxidative stress markers in the form of plasma mean lipidic peroxides pre- and post-treatment.

On Day 30 they saw a decrease in mean lipidic peroxide in the magnesium oxide group compared to the control group, suggesting that another mechanism for the improved ESGD scores could be reduced oxidative stress and increased scavenging of free radicals.

The researchers suggested supplemented magnesium oxide as a potential promising therapy for ESGD. While the data clearly showed an overall decrease in ESGD severity in the study population, it did not show the average decrease in ESGD scores per horse, so the researchers said it was unclear if some horses improved dramatically and some not at all, or if most affected horses improved at a predictable rate with the treatment. This data would help individual horse owners gauge the potential success of the supplement for their specific animal. More research is also needed regarding the role of reducing oxidative stress in mitigating ESGD.

Leleu noted she and her colleagues conducted this study in 2021 and a similar one in 2022, also with very positive results, but the latter has not yet been published. “The product, Timride-Up, was launched on the French market in 2023, with great success,” she said. “Trainers are very satisfied with Timride-Up and many report also the strong cooling effect, in relation with the influence of magnesium on the nervous system.” She said the next step is getting the product to market in the United States, noting it is currently under testing at Thoroughbred and Standardbred breeding farms in Kentucky and New Jersey.

The study, “Effect of a blend of magnesium oxide on Equine Squamous Gastric Disease in young trotter horses under training,” appeared in the Journal of Veterinary Science in November 2023.

Editor’s note: The study was funded by Timab Magnesium, but the authors declare no conflicts of interest.

Q: What are the clinical signs of ulcers in a horse? Will a horse’s behavior change dramatically if he has gastric ulcers?

A: Gastric ulcers can change a horse’s behavior and make them reluctant to work. These are typically the first signs of gastric ulcers that horse owners notice and relate to the pain from the gastric ulcers, but the pain is usually not severe enough that they show it all the time—they might only show it during certain activities.

One of the things we know is that there are two types of gastric ulcers. The gastric ulcers that occur in the upper part of the horse’s stomach, or what we call the squamous epithelium. Squamous ulcers are caused by acid splashing up on that part of the stomach because that part of the stomach doesn’t have adequate protection against acid.

Squamous ulcers can be exacerbated by infrequent meal feedings rather than constant access to food and exercise, which can cause the acid to splash on that part of the stomach. This is why we often see behavior changes and signs of pain or discomfort under saddle. These horses might also show unhappy or aggressive behaviors when they’re being tacked up, in anticipation of the pain.

The other types of gastric ulcers occur in the lower part of the stomach, or the glandular mucosa. The causes of these ulcers are less well understood but possibly could relate to decreased blood flow to this part of the stomach that impairs its healing ability. Clinical signs of glandular ulcers can also include behavior changes or decreased willingness to work, or possible recurrent mild signs of colic unrelated to work.

Horse owners should keep in mind that hay is less stimulating for acid production than grain and, so, a lot of times owners comment that horses eat their hay totally fine but start to not want their grain. They might not eat it at all or might just not finish it.

It is less common for an adult horse to have colic signs from gastric ulcers, but it is possible. I’ve seen bad gastric ulcers cause colic although, again, the signs of colic are usually more mild.

Q. My horse was recently scoped and diagnosed with gastric ulcers and is being treated for them. I have him on a gastric support supplement in hopes it will help reduce the risk of the ulcers recurring once the prescribed medication ends. Other than making the management changes that are often recommended for horses with a history of ulcers, is there anything else I could be doing to help him recover?

A. Gastric ulcers are a common and sometimes persistent issue in horses. While they most often occur in performance horses, they also affect horses at pasture, those not being worked, and those displaying no clinical signs. Several supplements on the market have shown promise under research conditions in reducing the number and severity of gastric ulcers. Using one of these products long-term might help reduce the risk of ulcer recurrence. As you state, management changes are often necessary and hopefully will minimize or remove stressors that might have been triggering ulcer development.

Researchers recently investigated specific and nonspecific biomarkers that could be used to diagnose equine gastric ulcer syndrome (EGUS), according to a study published in the January 2020 edition of the Journal of Equine Veterinary Science. Their goals were to find markers that could be assessed in blood samples that would indicate whether a horse did or did not have ulcers. This premise was based on human research that showed doctors could use serum pepsinogen and gastrin as diagnostic markers for the indirect assessment of gastritis. However, in this equine study, serum pepsinogen and gastrin showed no significant changes in horses with EGUS versus those that were healthy.

When the researchers looked at other potential markers, they found some interesting things. Proinflammatory cytokines, which are major contributors to tissue damage, were elevated in horses with EGUS. They also found horses with EGUS had significantly lower levels of nitric oxide (NO). NO is considered to be a gastroprotective compound because it controls the release of hydrochloric acid and works as an antioxidant against tissue-damaging free radicals.

While the researchers didn’t find any clear markers useful for diagnostic purposes, they did show horses with EGUS are under greater oxidative stress. They concluded that horses with EGUS might benefit from additional antioxidant therapy. Common antioxidants in the equine diet include vitamin E, selenium, and vitamin C.

Vitamin E is often low in horses without access to good-quality, fresh pasture most of the day. Dietary selenium might also be low depending on your geographic location and what additional sources you provide. Horses manufacture their own vitamin C, but in some instances they benefit from additional supplementation.

Based on this research you might wish to evaluate your horse’s antioxidant status and see whether you can offer additional support during the healing process. I recommend you work with your veterinarian to assess your horse’s vitamin E and selenium status via bloodwork, and then supplement as necessary based on the results. A qualified nutritionist can help you to assess the overall diet to make sure your horse’s needs are being met. If you decide to supplement vitamin C, look for the ester-C form, as it’s a little gentler on the stomach. Keep in mind that supplementing vitamin C might result in the horse producing less of his own, and if you stop supplementing in the future, you will need to do so slowly to allow endogenous levels to reestablish.

Overweight and obese horses are at a higher risk of developing other health concerns such as musculoskeletal disorders and metabolic problems. However, when feeding your horse for weight loss, it is important to avoid allowing them long period of time between meals to reduce their risk of hindgut problems. Frank Andrews, DVM, MS, Dipl. ACVIM, of Louisiana State University, in Baton Rouge, discusses the best ways to protect your horse’s hindgut while helping him lose weight.

This podcast is an excerpt of our Ask TheHorse Live Q&A, “Understanding Equine Hindgut Health.” Listen to the full recording here.

About the Expert

Frank M. Andrews, DVM, MS, Dipl. ACVIM

Frank M. Andrews, DVM, MS, Dipl. ACVIM, is a graduate of Washington State University College of Veterinary Medicine in Pullman, Washington, where he received a DVM and MS. After a year in private veterinary practice, he completed an Equine Medicine and Surgery Residency at The Ohio State University. After 20 years on the faculty at the University of Tennessee College of Veterinary Medicine, he is currently LVMA Equine Committee Professor and Head of The Department of Veterinary Clinical Sciences, as well as the Director of the Equine Health and Sports Performance Program at LSU Vet Med. Dr. Andrews is Diplomate of the American College of Veterinary Internal Medicine, Large Animal Internal Medicine. Dr. Andrews’ has clinical and research interests in gastric ulcers, gastrointestinal disease, and endocrine diseases and is involved in clinical equine practice and has been doing scientific investigation for over 35 years.

Q:  My horse is what many would consider a nervous type. He is easily unsettled by changes around the farm, and I can tell that going off property for shows, clinics, and trail rides makes him more nervous than usual. I’d like to add a preventive supplement to his diet to combat the effects of stress on his gastrointestinal system, but there are so many options on the market. What ingredients should I look for that would indicate a high-quality, effective supplement for preventing gastric ulcers?

A:  Equine gastric ulcer syndrome affects many horses. Remember that supplements do not fix underlying issues or causes so, first, take a whole-horse approach when managing individuals that frequently develop ulcers. Additionally, understanding the risk factors for different types of gastric ulcers and mitigating them helps prevent their recurrence. For instance, managing diet plays a more critical role with squamous gastric disease, whereas managing stress becomes more important with glandular gastric disease.

A plethora of anecdotal evidence exists on some ingredients found in gut support supplements and, in some cases, peer-reviewed research supports their use. Some ingredients shown to reduce a horse’s risk of developing gastric ulcers include L-glutamine, prebiotics, probiotics, aloe vera, marshmallow root extract, and slippery elm.

Gastric Buffers for Horses

Gastric buffer supplements might be useful for your horse in more stressful situations. For example, if your horse tends to be more stressed when trailering, you might give him a gastric buffer a few times that day. These products work only when administered multiple times per day due to their short efficacy period (generally two to four hours). Calcium carbonate, found in alfalfa, features prominently in gastric buffers. However, seaweed-derived calcium generally has a slightly longer efficacy period than calcium carbonate.

Key Equine Gastric Ulcer Supplement Ingredients

Outside of gastric buffer supplements for the stressful days, adding an all-around gut support product to your horse’s diet might reduce the impact of daily stress on his gastrointestinal tract. Manufacturers often include L-glutamine, a nonessential amino acid, meaning horses can synthesize it on their own. But if your horse stresses regularly, supplementing L-glutamine can help mitigate the effects on the gastrointestinal tract. The anti-inflammatory properties of aloe, slippery elm, and marshmallow root extract can also reduce oxidative stress and soothe the gastrointestinal tract.

Prebiotics and Probiotics for Horses

Equine nutritionists typically recommend prebiotics and probiotics for longer-term gastrointestinal support. Some evidence surrounding these products remains anecdotal, so find a supplement backed by peer-reviewed research. Probiotics consist of live, beneficial bacteria already present in the horse’s digestive tract, while prebiotics provide nourishment for these bacteria.

Purchasing a Gastric Ulcer Supplement for Your Horse

When selecting a supplement for your horse, reach out to the company to ask about peer-reviewed research on their product. If the company has invested in quality research, they will be more than happy to share it with you.

Prior to purchasing any supplement, carefully read the label. For example, the labels on high-quality pre- and probiotic products should tell you the specific bacterial strain used, the number of colony-forming units (CFUs), and an expiration date because probiotics are live microorganisms. As for daily supplements, review the guaranteed analysis on the product and compare the active ingredient amounts in products. For example, while many products contain both aloe and L-glutamine, the concentration of these ingredients can vary significantly.

Take-Home Message

Administering a gastric buffer on stressful travel days and using a daily gastric support supplement can help your horse combat the negative impacts of stress on the gastrointestinal tract. Before purchasing, be sure to thoroughly read the label of any supplement and ask the company to share peer-reviewed research supporting the product’s efficacy.

Q: My horse has been diagnosed with equine gastric ulcer syndrome. Is it true that alfalfa is better than grass hay for horses with ulcers?

A:  The short answer to your question is yes, adding alfalfa to your horse’s diet might be beneficial. Researchers at Texas A&M assessed the incidences of gastric ulcers in horses fed a pelleted grain concentrate and either coastal Bermuda (CB) grass hay or alfalfa. The horses in the study were Quarter Horse yearlings housed in small dry lots and subjected to exercise using a mechanical walker. They found the horses fed CB grass hay experienced a significant increase in ulcer score severity during the study period compared to the alfalfa-fed yearlings.

The composition of the alfalfa seems to help reduce the incidence of ulcer development and severity. Alfalfa is higher in protein and calcium than most grass hays, both of which act as buffers in the stomach, raising the pH level. Additionally, alfalfa is higher in a structural carbohydrate called lignin that is also thought to be beneficial. Other research has shown horses fed alfalfa hay and grain had significantly higher stomach pH for five hours after feeding and fewer/less severe gastric ulcers than horses fed brome hay. Raising the pH of the gastric contents reduces irritation of the sensitive squamous gastric tissue or existing gastric ulcers.

Not all barns offer alfalfa, and it might not be appropriate for all horses because it is higher in calories than most grass hays. Feeding too much alfalfa might result in a diet with very high crude protein and calcium levels, which can also be inappropriate for some horses. Researchers recommended feeding 1 pound of alfalfa to horses weighing 1,100-1,300 pounds after a grain meal because feeding grain, especially grains with higher nonstructural carbohydrate contents, lowers gastric pH, making the stomach more acidic.

Feeding a small amount of alfalfa is most easily done using alfalfa pellets or chopped alfalfa, especially if your barn does not provide alfalfa hay, because they are easily purchased in bags. Pellets or chopped alfalfa can be fed with grain meals or before exercise.

It is possible that very stemmy alfalfa could irritate the stomach. Research comparing the effects of particle size on the gastric mucosa in foals before and after weaning showed lesions at the pylorus were significantly more severe in the group fed alfalfa chaff (chopped alfalfa) than those fed alfalfa pellets. It’s important to note that in this study, the foals were fed just over 40% of the forage in their diet as alfalfa chaff or 37.5% of the forage as pellets, with the control group being fed 100% of their forage as grass hay. A subsequent study in a very small number of mature horses looked at the impact of feeding all the forage as either grass hay or chopped alfalfa and found no significant difference in glandular ulcer scores between the groups.

This research provides useful information as to the possible effect of alfalfa forage particle size on gastric health, but it is worth noting that in nonresearch settings, alfalfa chaff is typically fed as a supplement to the long-stem forage in much smaller quantities than was researched. Additionally, not all chaff is equal, in that some is quite soft and some is quite harsh. Larger forage particle sizes, such as those in chaff or from long-stem hay, will create a better raft of fiber on top of the stomach contents than pellets. Such a raft is important for reducing the likelihood of stomach acid splashing the sensitive squamous tissue, especially during exercise. Longer stems also require more chewing, which secretes saliva—a good stomach buffer.

If your horse is a good candidate for substituting some of the grass hay in the ration with alfalfa and your barn offers alfalfa, this might be a useful tool. Keep the alfalfa to no more than about 25 to 30% of the total forage intake to control total calcium and protein in the diet. If alfalfa hay is not a viable option for you or your horse, consider adding a small amount of alfalfa pellets or chopped alfalfa hay. Based on the particle size research, avoid chopped alfalfa if your horse has been diagnosed with pyloric ulcers. If alfalfa is not an option for your horse, there are many good commercial buffering feed supplements available on the market that use marine-derived calcium, which has been shown to be a very effective gastric buffer.

It is important to keep in mind that forage type and form is only one part of managing gastric ulcer disease in horses. Evaluate your entire management program to see where you can reduce stress (reductions in training intensity, isolation, negative human interactions, etc.), improve overall feeding management (small frequent meals, use of slow feed hay-nets), and alter environmental factors, such as increasing pasture turn-out. By conducting an inventory of your horse’s entire lifestyle and management and making changes where you can, your horse will have the best chance of gastric ulcer recovery and prevention.

Q: My 10-year-old mare had colic surgery a few months ago and developed gastric ulcers during her recovery. What advice do you have for managing her digestive issues going forward?

A:  Recovery from colic surgery is difficult enough without the addition of ulcers. Stress can predispose a horse to developing gastric ulcers, and surgery is definitely stressful for any animal.

A horse’s stomach is divided into two parts. The glandular region, or the lower part, continually secretes acid. It is somewhat protected from ulceration because the cells in this region also secrete mucus, which forms a protective layer. The upper portion of the stomach is called the squamous region. The cells in this region don’t produce acid or mucus, but acid from the lower region can reach the upper region and cause ulcers to form.

Not all horses with ulcers show outward signs or, when they do, they’re subtle. Some signs you might observe include poor appetite, poor hair coat, poor performance, lying down frequently, teeth-grinding, and changes in attitude. Some horses might attempt to lie on their backs because it appears to provide relief from the ulcer pain.

The only way to definitively diagnose ulcers is having a veterinarian perform a gastroscopy on your horse with an endoscope, which is a type of camera inserted into the stomach through the nostril. If your horse was diagnosed with ulcers, she was likely prescribed medication, such as omeprazole. You should also work with your veterinarian and an equine nutritionist to make modifications to your horse’s diet to help prevent ulcers in the future.

Horses produce acid from the glandular region continuously. So, the goal of dietary management is to buffer acid production. A horse’s saliva contains bicarbonate, which helps buffer this acid, but horses only produce saliva when they are chewing. If you feed your horse some form of concentrate, consider higher fat and lower grain options, and divide rations into multiple small meals. Smaller meals will help the horse produce less acid.

Good-quality hay is vital to preventing ulcer development in at-risk horses. A small amount of legume, such as alfalfa, might be beneficial because of its higher calcium content. Forage requires more chewing than concentrates, so the horse will produce more saliva. In addition, forage will float and form a “mat” on top of the stomach contents, which will provide additional protection against acid reaching the squamous part of the stomach.

You can also implement management practices that can help prevent ulcers from forming. The goal is to decrease your horse’s stress levels as much as possible. For most horses, having some turnout time, especially with other horses, can reduce stress levels. Maintaining a consistent routine, such as feeding time each day, can also reduce stress. Make sure your horse always has hay available to her when she is traveling and at competitions, because chewing forage will help reduce acid buildup in the stomach.

These diet and management recommendations can help reduce the incidence of gastric ulcers in your mare. An additional benefit is these recommendations should also decrease the incidence of colic. Keep an eye out for any behavioral changes that might indicate ulcers are forming and be proactive. If you have any concerns about ulcers forming, ask your veterinarian to do an examination and possibly an endoscopy for diagnosis.

Q.​ I’m in the process of importing a horse from Europe and concerned about how I should feed him once he arrives at my barn. From what I know, he currently eats haylage and some kind of sweet feed. I assume that while he is in quarantine he’ll receive grass hay of some kind. Once he leaves quarantine, he has quite a long road trip to get home, and the hauler will also feed grass hay, although possibly a different type. With all this change I’m concerned about colic and gastric ulcers. How would you suggest I feed him, and is there anything I can do to limit the risks of colic and ulcers?

A. Congratulations on your new horse! I’m sure you must be very excited but also quite nervous. The good news is many horses are imported from Europe, and most do very well. My advice is to keep things simple. He’ll need time to adjust to a new diet and an entirely new routine and way of life. Some limited research suggests that horses might be affected by jet lag, so that is something to keep in mind, especially as it relates to his athletic ability.

As the saying goes, “prevention is worth a pound of cure.” I would start off by reaching out to the quarantine facility and shipping company to see whether they would be willing to administer Ulcergard, which is the over-the-counter preventive Gastrogard (omeprazole) dose. This should help reduce gastric ulcer risk. I’d also consider paste forms of digestive tract supplements that contain good prebiotics such as yeast, because these help stabilize the hindgut environment. The paste form makes it easy for staff to administer without having to provide any kind of feed.

Lastly, keeping horses hydrated while traveling is important, so ensuring adequate daily sodium intake is vital. This can be achieved by feeding salt; however, an electrolyte might be more palatable. Once again, these can be found in paste form for easy administration while in quarantine and on the road.

Once your new horse arrives at your barn, continue with these precautions. At this point you don’t necessarily need to use the paste forms of the products, but I would continue with the good prebiotic and hydration support. The hydration support should become part of your daily routine, and I recommend continuing with the prebiotic for at least several weeks. Your veterinarian can advise you on how long to continue the ulcer preventive, but typically one to two weeks after arrival is recommended.

As for overall diet, you could try to find out what type of grass hay the quarantine and shipper will use. But the reality is even the same type of hay can differ nutritionally. Therefore, this is probably not worth worrying about, because it’s out of your control. Find a good, clean grass hay, and start by feeding at least 1.5-2% of the horse’s body weight per day. Quarantine records should provide you with an accurate weight, because your horse may have been weighed upon arrival and departure.

If you want to feed something in a bucket in addition to hay, start with grass hay pellets or soaked beet pulp. After the initial transition has gone smoothly and your horse has been with you for a week or so, you could then move to feeding a ration balancer in addition to the hay. This feed has a small daily serving size but provides all the necessary minerals your horse might need, as well as additional quality protein. The only other nutrient you might need would be vitamin E, but that is something I would have your veterinarian check for and then supplement as necessary. You might also choose to add a source of omega-3 fatty acids to the diet.

Some things to keep in mind as you think about feeding your new horse are that very few horses in Europe receive alfalfa hay. If they do get alfalfa, it’s typically chopped and fed mixed with their grain ration. Therefore, I recommend you avoid alfalfa initially. If you do decide you want to feed it, start it very gradually. Horses in Europe often receive much more concentrate sweet feed than we now feed in the United States. Additionally, in my experience, the grass hay in Europe often isn’t the quality we have here, so there’s a greater reliance on concentrate feeds. Just because your horse ate a lot of textured, high-grain feed there doesn’t mean you need to feed as much. Lastly, don’t assume your horse had pasture access in Europe. If you’re considering turnout on grass, introduce pasture slowly.

With careful planning and good management, your new horse should settle in well. I wish you both all the best and hope you have a great time getting to know each other.

Q: I’ve always been taught to not ride a horse right after it’s been fed. However, I have a mare who has gastric ulcers, and my veterinarian recommended that I feed her prior to riding (specifically, alfalfa). So which is it—feed or don’t feed before riding?

A: While it’s true that it is typically best to avoid feeding horses concentrates (especially those high in starch) within a couple of hours of riding due to the effect this can have on available metabolites during exercise, allowing access to forage has a number of benefits. Remember horses are designed to eat fibrous plant material almost constantly, while at the same time traveling considerable distances.

As a result of this constant forage consumption, horses have evolved to secrete gastric acid into their stomachs on a continuous basis. Acid is secreted whether they are eating or not and is needed to activate enzymes involved in protein digestion. The act of chewing causes the release of saliva, which contains sodium bicarbonate and calcium—both of which act to buffer stomach acid. It’s a brilliant system, because the constantly secreted stomach acid is buffered by the continuous release of saliva from chewing.

But what happens when, instead of continuous access to forage, we meal-feed our horses? The stomach acid is secreted as always, but there is no longer a steady saliva supply. That’s because most horses finish their allotted hay meal in at most a couple of hours unless eating out of a slow feeder. This leaves the stomach environment to become increasingly acidic and raises ulcer risk.

If we happen to come and ride our horses at this time, not only is there a more acidic environment in the stomach, but there’s also less fiber to prevent movement of stomach fluid. The stomach is never completely full, and the fluid portion of the stomach contents sits at the bottom of the stomach with the larger feed particles such as chewed hay floating on top, forming a sort of mat. This mat helps to prevent the stomach acid from sloshing around. The mat is particularly important because the area of the upper stomach, above the level of the stomach acid, is the most at risk of ulcers and has very little protecting it other than this mat suppressing acid movement.

The glandular cells in the lower two thirds of the stomach that secrete acid also secrete mucin and bicarbonate, so they are protected (note that ulcers can still occur here but they are less common). But the cells of the upper squamous portion don’t secrete acid and therefore have very little protection. They’re not designed to come in to contact with stomach acid. As we ride the stomach acid sloshes about and—if there is not a good fibrous mat—it will come into contact with those unprotected squamous cells, leading to an increased risk of ulceration.

If it has been several hours since your horse last had access to hay or other forage, I recommend offering some hay prior to riding. While consuming forage might increase body weight, which some believe is a negative attribute for horses needing to work at speed, researchers have showed that feeding small amounts of hay or grazing prior to exercise doesn’t negatively impact performance.

If you have a choice in hay available, I recommend offering access to alfalfa before exercise. The reason for this is that studies have found that alfalfa’s high calcium and protein content have additional buffering capacity, which researchers believe help further reduce ulcer risk over other forms of hay. If your barn does not feed alfalfa or you don’t want your horse to get a full flake of alfalfa hay, then feeding a pound or two of alfalfa pellets is likely to be sufficient. You could offer these while you’re grooming and preparing to ride.

Gastric ulcers can affect horses of all ages and breeds and often result in economic losses due to the cost of treatment and loss of training and competition time. 60 to 90 percent of performance horses suffer from gastric ulcers due to the stressful nature of their training and competition schedules. Clinical signs of gastric ulcers can include weight loss, inappetence, dull coat, or behavior problems both on the ground and under saddle. Understanding how to identify potential signs of gastric ulcers is crucial to reducing your horse’s discomfort. If you suspect your horse has gastric ulcers, work closely with your veterinarian so they make an accurate diagnosis and develop an effective treatment plan. 

July is Equine Gastric Health Awareness Month on The Horse, where we’ve partnered with SmartPak to help educate owners about equine gastric health. Look for equine gastric health-related content all month on TheHorse.com, our Facebook page and Twitter feed, and in our e-newsletters. 

Equine glandular gastric disease (EGGD) can negatively affect the health and performance of sport horses. The pain caused by this condition often prevents affected horses from performing well in competition, leading to welfare concerns and a negative economic impact for owners and trainers alike due to cost of treatments and loss of training and competition time. In addition to medical treatment led by a veterinarian, most horses with EGGD benefit from nutritional and management changes to support treatment and promote long-term ulcer prevention.

Alfalfa vs. Concentrate for Horses with EGGD

To observe the effects of management on EGGD, Samy Julliand, PhD, director of animal nutrition research at Lab to Field, in Dijon, France and his coauthors studied 77 French trotters, ranging from 2 to 3 years old, from four different training centers. The researchers selected these training centers because they had comparable training and feeding management—all horses in the study exercised five to seven days per week, with one to three days of fast work on a track.

At each center, researchers divided horses into two groups based on baseline ulcer scores, age, and sex. They then randomly assigned each horse to a control group to stay on their usual diet throughout the study or an alfalfa treatment group that had half their concentrate feed replaced with alfalfa pellets. An outside blinded veterinarian performed gastroscopy on each horse on Days 0, 21, and 42 of the study, scoring glandular ulcers on a scale of 0 to 4, with 0 being no ulcers.

On Day 0 the researchers saw no significant relationship between horses’ overall energy intake (how many kilocalories or megacalories) in their diet and EGGD, but they noticed horses that consumed more simple sugars received lower scores. “Prior to the study, based on previous knowledge, we had hypothesized that the higher the carbohydrate content of the diet, the higher the glandular scores,” said Julliand. “We were surprised to observe that this was not the case in this study … and, on the contrary, that simple sugars were associated with a lower prevalence of glandular ulcers. It’s possible that this is associated with the microbiota favored by these substrates.” Julliand and his team plan to further investigate this aspect in the future.

Also on Day 0, the veterinarian found glandular ulcers scoring at least 2 in severity in 13 of the 77 horses. On Day 21, three of the 31 control horses had glandular ulcers with a severity of at least 2, while none of the 28 horses in the alfalfa group had ulcers with a severity of 2 or greater (some were unable to participate in this gastroscopy). On Day 42, 12 control horses and four alfalfa group horses had glandular ulcers.

The researchers noted a positive relationship between feeding alfalfa pellets and a decreased incidence of EGGD by Day 42 of the study. They believe this was due to the overall decrease in starch consumption when alfalfa pellets replaced half the concentrates and the high calcium concentration of alfalfa, which buffers acid production in the gastric environment.

Managing Horses With EGGD

While the researchers do not have exact management recommendations for owners managing glandular ulcers in horses, the results helped them begin to form possible advice. “Even if the optimum rate of integration and form of presentation have not yet been determined, dehydrated alfalfa could be integrated into the rations of horses at risk for EGGD,” said Julliand. “It could be beneficial for their health, without impairing the performance of athletes.”

Future Glandular Ulcer Research

Julliand and his team plan to repeat this study and include a medical treatment group as well as a larger number of ulcerated horses. He said they also hope to further explore the diet-microbiota-gastric health relationship because this knowledge might be useful for developing new ways to prevent or treat glandular ulcers in horses.

Take-Home Message

Researchers are confident a strong relationship exists between a horse’s dietary management and incidence of EGGD. Julliand said more work needs to be done on the relationship between gastric microbiota, gastric health, diet, and management, but that he and his team believe dehydrated alfalfa shows promise in preventing glandular gastric ulcers.

The study, Effect of Diet Composition on Glandular Gastric Disease in Horses, was published in the Journal of Veterinary Internal Medicine in August 2023.

Not all gastric ulcers in horses have the same signs, risk factors, and treatment approaches. Specifically, equine glandular gastric disease (EGGD) involves ulcers in the lower portion of the stomach, and often manifests during tacking or riding in response to pain or expected pain during these activities. Owners suspecting their horses might have EGGD need to work closely with their veterinarians to arrive at a diagnosis and treatment plan—which is different than that for squamous ulcers—to avoid long-term welfare concerns.

A horse’s stomach is a single chamber with two distinct regions—upper and lower. The upper is lined with squamous mucosa, while the lower is lined with glandular mucosa. “It is really important that we differentiate ulcer type because the factors that drive disease in the squamous mucosa are very different from the factors that drive disease in the glandular mucosa,” says Ben Sykes, BSc, BVMS, MS, MBA, Dipl. ACVIM, PhD, FHEA, associate professor in equine medicine at Massey University, in New Zealand. Determining what factors initiate each horse’s disease can help veterinarians create an effective treatment and management plan.

Risk Factors for Equine Glandular Gastric Disease

When considering your horse’s gastric issue, his time spent grazing and consuming hay, the nonstructural carbohydrate (NSC) content of the diet, and timing of exercise are important factors. However, they play a much larger role in squamous gastric disease than glandular.

“Glandular gastric disease is very different from squamous,” says Sykes. “We have no epidemiological evidence to say that diet is a major contributor to disease. It might be something we use as a therapeutic target during the long-term management phase but, really, diet is not the main driver of disease.” Instead, EGGD is more of a behavioral and stress-based disease.

“Stress plays a role in the development of both squamous and glandular gastric disease, although the scientific evidence is stronger in the case of glandular disease,” says Robin van den Boom, DVM, PhD, Dipl. ECEIM, head of the equine medicine team at Utrecht University, in the Netherlands. “Some of this stress may be related to interaction with humans as trainers, the number of caretakers, and the time interacting with humans (which) all increase the prevalence of gastric disease.”

The relationship between exercise and glandular ulcers differs from the relationship between that and squamous ulcers. “For squamous disease it is a cumulative effect. It is the number of minutes of exercise we do during a given period, say a week,” says Sykes. “For glandular disease, it’s the number of times we exercise, and the absence of rest days.” Horses that exercise five or more times per week are at a significantly higher risk of developing glandular gastric disease. “It is advised to give horses two or three rest days per week to assist in preventing glandular gastric disease,” says van den Boom.

Clinical Signs of Equine Glandular Gastric Disease

Horses that have EGGD do not typically show a change in appetite or unexplained weight loss. “Most horses with glandular disease have an excellent appetite and a normal body condition,” says Sykes. “The symptoms that we see tend to be behavioral and are often associated with aversive behavior during riding or tacking up.” These clinical signs indicate glandular disease is primarily a pain-based disease. If it seems like your horse is dealing with pain, work closely with your veterinarian to determine the best course of action.

Diagnosing and Treating Equine Glandular Gastric Disease

If veterinarians suspect a horse has EGGD, they perform a gastroscopy to confirm it. “Scoping is valuable for several reasons,” says Sykes. “First, it assists us in getting an accurate diagnosis. With it recognized that it is a pain-based behavioral condition, in the welfare interests of the horse, we want to get an accurate diagnosis as soon as possible. So, gastroscopy is a critical element in doing that.” A definitive diagnosis equips your veterinarian with the information needed to design the best treatment plan.

“Glandular lesions usually take longer to heal (than squamous), and the first line of treatment is omeprazole and sucralfate, whereas squamous disease is treated with omeprazole only,” says van den Boom—omeprazole alone is relatively ineffective for treating glandular disease. “Treatment with misoprostol may also be considered for glandular lesions. With the treatment duration and healing being longer for glandular disease, this means that repeat gastroscopy may be better performed after six to eight weeks as opposed to three to four weeks which is seen when treating squamous disease.”

Your veterinarian will recommend treatment approaches based on your individual horse’s needs.

Preventing Equine Glandular Gastric Disease

To prevent the recurrence of glandular disease, become familiar with the established risk-factors. To review:

• Exercise: Again, the cumulative amount of exercise is not as important as the frequency. Your horse needs a minimum of two rest days per week—ideally, three—to reduce his risk of EGGD.

• Stress and Environment: Minimizing your horse’s stress is a critical aspect of long-term management. “Optimizing the horse’s environment should be a central focus of glandular disease prevention,” says Sykes. “This means factors like companionship, the ability to cohabitate with other horses, and the ability to engage in natural behavior (e.g., mutual grooming).”
  
  “Although we don’t think we know well enough what the most common stressors are, it is advised to provide a regular daily routine and keep an eye on how horses interact,” adds van den Boom.
  
• Human Handling: When reducing stress in a horse’s life, consistency is key. Horses prefer consistency in their handlers, riders, and routine, says Sykes. But horses live in a variety of situations and respond differently to change. Some horses have a multitude of riders and do not exhibit any health issues, while other horses are more sensitive to inconsistency. “It is very easy to understand, particularly, horses like dressage horses, where they are trained to respond to an aid and release from the aid,” says Sykes. “If you change the rider and they’re pressing slightly different buttons, the horse is trying to do the right thing but not getting its release, this can become behaviorally frustrating for the horse, and contribute to behavioral stress.”

Long-Term Management of Equine Glandular Gastric Disease

When horses have glandular disease for months or years, other related issues might surface. “Many of these horses with glandular disease may have a learned behavior so, even when the ulcers have been treated, we may see an anticipatory pain-based response,” says Sykes. “Sue Dyson completed research on orthopedic lameness where the horses that were lame during exercise showed aversion behavior to tacking up. This tells us that it’s not the tacking up that is painful, but they’ve made an association to the pain that will occur during exercise.”

To address these responses, owners can work to reduce their horses’ stress. “Modalities such as massage, music to change the environment, and pre-exercise feeding to change the event from a negative experience to a positive experience are valuable go-to strategies,” says Sykes.

Supplements can also play an important role in the long-term management and presentation of glandular disease. “Critically, when selecting supplements, it is essential that we choose ones with peer-reviewed scientific evidence to support their use,” says Sykes. “This gives us our best chance of a positive outcome, which in turn benefits the owner financially and the horse from a welfare perspective.”

Take-Home Message

Understanding the common clinical signs, established risk factors, and prevention strategies for glandular gastric disease helps optimize welfare of affected horses. Prioritize reducing stress, maintaining a consistent handling schedule, giving the horse rest time, and improving the environment. If you suspect your horse might be struggling with pain or any other health issue, be sure to contact your veterinarian immediately.

Equine glandular gastric disease (EGGD), which causes ulceration in the lower, more protected area of the stomach, impacts horse performance and welfare considerably. Researchers have studied this condition for decades to better understand its mechanisms and develop new treatment methods.

Linda Paul, DVM, Dipl. ACVIM-LA, earned her PhD at Louisiana State University’s (LSU) School of Veterinary Medicine in biomedical and veterinary medical sciences, in Baton Rouge, in 2023 after she and her research team explored potential differences between the gastric microbiomes of healthy horses versus those with ulceration in the glandular portion.

Evaluating the Gastric Microbiome of Healthy vs. Ulcerated Horses

In this field study the researchers divided 57 horses into two groups. Group 1 consisted of 25 controls—horses without gastric ulcers. Group 2 was made up of 32 horses with mucosal disruption in the glandular part of the stomach (grade ≥ 2/4). Heidi Banse, DVM, PhD, Dipl. ACVIM-LA, associate professor of equine medicine at LSU, evaluated and scored the horses’ ulcers via gastroscopy, the gold-standard diagnostic method for equine gastric ulceration.

The researchers then biopsied the stomachs of all 57 horses, taking samples from healthy mucosa and from areas of glandular mucosal disruption, where applicable. They extracted bacterial DNA using a purpose-built commercial kit and found modest differences between the microbiota of the glandular mucosa in control horses and EGGD horses.

Specifically, they saw enrichments (growth) of the bacteria Actinomycetota, Staphylococcus, Lawsonella, and Streptococcus salivarius in control biopsy samples, while they found enrichments of Lactobacillus equigenerosi and Actinobacillus in EGGD ulceration samples.

Understanding Microbiome Differences in Horses

“The biological action of the enriched bacteria on the glandular mucosa for each group of horses is actually unknown,” said Paul—in other words, they don’t know its purpose. “For example, L. equigenerosi—found in this study in the EGGD ulcerations—was previously identified in horse feces. As a group, Lactobacillus species have various biological properties that can be good or bad.”

Banse recommends scientists conduct further research on the presence of L. equigenerosi in the equine glandular stomach to determine whether its presence has a positive, negative, or neutral impact on EGGD.

The Role of Exercise in EGGD

Beyond the gastric flora, Paul and her team also took a whole-horse look at potential risk factors for EGGD. They found that exercising more than three hours a week increased a horse’s risk of developing gastric ulcers.

The researchers are not sure why that’s the case. While researchers on previous studies have established that dietinfluences the gastric microbiome, exercise was not a factor directly associated with changes in the equine gastric microbiome in this study.

This lack of correlation suggests other mechanisms contribute to exercise’s influence on the development of EGGD, Paul said. She and her team hypothesized that decreased blood flow to the gastrointestinal tract during exercise makes the stomach more susceptible to dysfunction and disease.

Take-Home Message

Scientists need more research to draw definite conclusions from these preliminary findings. “Microbiome research is incredibly complex, especially when working with a population of client-owned horses at different barns, since different diet and management strategies can affect the gastric microbiome,” said Paul.

“Being able to identify bacterial differences between horses with and without EGGD in this study was nonetheless very exciting because we suspected from prior studies that differences existed,” she added. “Understanding those findings is another step forward in our comprehension of EGGD, a condition that impairs the athletic performance and overall health of so many horses.”

Horses evolved to eat frequent, small roughage meals throughout the day, so why do we only feed them twice?

Take a minute and picture horses in the not too distant past or in the wild today. They have no access to grain (concentrate) meals, and they graze for a substantial portion of the day. For managed horses, however, it is common to feed them two meals per day made up of a portion of concentrates and a serving of hay. Some of the more intensively managed horses have limited access to daily turnout and pasture, which means they might spend the bulk of their days in a stall without food between their meals.

“What we’ve done, without bad intention, is taken a continuous-feeding animal and turned them into meal-feeding animals,” explains Anthony Blikslager, DVM, PhD, Dipl. ACVS, professor of equine surgery and gastroenterology at North Carolina State University’s College of Veterinary Medicine, in Raleigh.

Even if those quality meals provide all the calories and nutrients a horse needs, they are not the healthiest option based on the horse’s gastrointestinal (GI) structure and function.

“How and when a horse is fed is just as important as what a horse is fed,” says Laurie Lawrence, PhD, professor in the department of animal and food sciences at the University of Kentucky, in Lexington. 

In this article we’ll review some of the basic features of the equine GI tract, describe why less frequent meal feeding can be detrimental to your horse’s health, and discuss alternative feeding management strategies.

The Gut: A Brief Overview

When on pasture, horses graze about 60% of their time, or 14 to 16 hours per day. This means horses continuously consume small amounts of forage, which provides a constant trickle of food to the stomach.

Because horses evolved as these grazing animals, their stomachs are quite small. The stomach only holds 3-5 gallons (18 liters), representing only 7-8% of the capacity of the entire digestive tract. Forage consumed during grazing moves relatively quickly through the stomach and small intestine to the hindgut (the cecum and large intestine), where bacteria and other microorganisms that make up the intestinal microbiome ferment it. Fermenting fibrous feeds is what provides horses with the bulk of their energy for bodily processes. 

Because fermentation is so important, perhaps it is not surprising that the hindgut is large compared to the stomach. The cecum has a capacity of 7-10 gallons (26-38 liters), while the large intestine holds a whopping 20 gallons (75 liters).

Why Feeding Infrequent Meals is Detrimental to Horse Health

Water Shifts and Colic

Typically, owners go out to the barn in the morning and feed horses a meal of concentrate with a “side” of forage.

“This type of meal moves rapidly through the small stomach and along 70 feet of small intestine to reach the hindgut within three to four hours,” says Blikslager.

The hindgut, however, is expecting fibrous material, not the highly fermentable sugars found in concentrates.

“If you ferment concentrate it creates a lot of soluble sugars, which draw a very large volume of water into the hindgut from the circulatory system and extracellular fluid,” says Blikslager. “It’s an unbelievable amount of water, about 150 liters or 40 gallons, being pulled into the large intestines in a very short period of time.” 

That excess water does one of two things: It causes diarrhea (evidence of colitis) and dehydration, or the body resorbs it all from the large intestine, leaving the horse at risk of impaction with the dried, fermenting ingesta that remains in both the cecum and large intestine.

“It’s just not a good idea to have all that water flux,” says Blikslager. “With a more sensible meal, the water fluxes are much more subtle. Many horses don’t deal with those fluxes well.”

Equine Gastric Ulcer Syndrome

In addition to being small relative to the horse’s size, the equine stomach is also unique because it secretes acid all day, every day. This is unlike a human stomach that only secretes acid when there is food in it.

“When a horse is fed roughage, it buffers the acid,” explains Blikslager. “But if you meal feed then it doesn’t buffer the acid, and horses are at risk of developing ulcers in the upper or squamous region of the stomach.”

Indeed, researchers have shown that intermittent feeding, high sugar and starch intake, and prolonged time without forage access are all risk factors for squamous disease (Galinelli et al., 2019). More specifically, a low forage intake (less than 1% dry matter per ideal body weight) and high sugar/starch intake (greater than 2 grams/kilogram body weight/meal) were associated with squamous gastric ulcers.

Changes to the Intestinal Microbiome and Leaky Gut

“Feeding horses meals with concentrates topped off with some forage is like feeding them a highly digestible food like Cap’n Crunch cereal instead of Shredded Wheat,” Blikslager says. “The horse is going to have a whole different population of organisms in the intestinal microbiome trying to ferment those two cereals. The shredded wheat will cause less of a shift in the microbiome because it is closest to the type of fiber the horse is used to.”

In contrast, Cap’n Crunch will cause a surge in a different population of microbes. The intestinal microbiome tries to ferment this type of feed, which creates inflammation.

“Inflammation in the gut causes a condition called leaky gut,” Blikslager explains.

Leaky gut occurs when the tight junctions that connect the cells forming the wall of the GI tract break down and become “leaky.” These cells and tight junctions are the only layer of protection between the inside of the intestinal tract and the horse’s circulation.

Thus, with leaky gut, GI tract contents seep between the intestinal cells into the circulatory system. Leaky gut may have far-reaching effects, including behavior changes, weight loss, poor performance, loose stool, chronic or recurrent colic, and laminitis.

Prioritize Roughage

Again, somewhere along the way, many horse owners radically altered how they feed, offering concentrate feeds with the forage component almost as an afterthought.

“We need to design our management scheme around a more continuous roughage intake rather than concentrate meals,” says Blikslager. “We want to always drive towards reducing the amount in the concentrate portion of the meal versus the amount in the hay or grazing. We should always try to think about roughage first.”

Lawrence agrees, adding, “Generally, horses should be eating forage in a nibbling situation, over the course of hours. Even if hay is offered just twice a day, it usually takes a horse a while to consume the offered amount. When hay or pasture is freely available, horses will be eating throughout the day … that is, they usually start and stop, start and stop.”

Slow feeders can help extend the time horses consume feed, and horse owners can also use round bales in their fields, especially when they are maintaining horses on dry lots or when the pastures are grazed down. Just be sure to seek a less nutrient-dense hay for any horses that are overweight or are participating in a weight-loss program.

Also bear in mind that minimizing meal feeding does not mean forage must be available 24/7.

“For example, horses that work for several hours a day are not going to be eating continuously while they are in the field or on the trail,” Lawrence says. “On the other hand, more or less continuous forage availability may be desirable for horses with nothing to do all day.”

This begs the question, does your horse even need a concentrated feed as a meal?

“True concentrates are fed to provide calories and nutrient fortification (vitamins, minerals, and sometimes protein),” says Lawrence. “If a horse is overweight, she may not even need a true concentrate. She may be fine with forage and a ration balancer that provides the nutrient fortification. When a horse is too thin or has an increased energy demand, providing a more digestible and nutrient-dense hay can increase calorie intake without increasing concentrate intake.”

“If owners still feel the need to feed a horse a meal, then we can lean more towards a pelleted feed, which has pieces of fiber,” adds Blikslager. “This will help us try and get away from soluble starch as much as possible.”

Small, Frequent Meals Improve Nutrient Digestibility and Glucose Metabolism in Horses

Researchers on a study published in 2021 found that increasing feeding frequency improved nutrient digestibility (Direkvandi et al.). They again observed that horses under natural conditions consume small amounts of high-fiber, low-starch feed per meal. They also noted that when feeding a large amount once a day, for example, the meal moves through the GI tract faster resulting in decreased nutrient absorption.

To explore this concept further, Direkvandi and colleagues studied 16 Turkmen horses fed either two, four, six, or eight meals in a 24-hour period. All horses received the same total amount of food (a mixture of 70% hay and 30% concentrate) per day regardless of schedule. The team collected fecal samples on Days 22 and 28 of the study and analyzed them for nutrient digestibility.

With increasing feed frequency, digestibility increased—notably, the digestibility of ash-free detergent fiber and ash-free neutral detergent fiber (measures of feeds’ cell walls, or structural carbohydrate components on an organic matter basis). The study authors attributed increased digestibility in the horses fed more meals per day to the decreased passage rate of feed material through the GI tract, the increased impact of digestive enzymes in the small intestine, and the increased amount of time the nutrients fermented in the large intestine.

They concluded that feeding more than two times per day increased digestibility; however, they observed no statistical difference between digestibility in horses consuming four and six meals per day.

This research team also evaluated serial blood glucose concentrations throughout Day 27 of the study. Glucose decreased significantly with increasing feeding frequency. Further, they observed a steadier state (less fluctuation) in blood glucose levels with more frequent feeding.

The researchers agreed that this state is likely to improve the well-being of horses and activity performance of a horse kept in a stall. It is comparable to the more natural condition where horses evolved to eat small and frequent meals throughout the day to spend 16-18 hours per day grazing.

Take-Home Message

“Feeding horses twice a day may be labor efficient, but it is not the most desirable situation for the horse,” says Lawrence.

“We understand why horses are fed meals, and horses should be fed to meet their caloric needs for their level of body condition and performance, Blikslager adds. “However, always thinking roughage first, then concentrate will hopefully help horse owners to think about the best approach to nutrition. There are increasingly better ways of getting roughage to horses, including slow feeding devices for the field and stall.”

This article is from the Preventive Care 2024 issue of The Horse: Your Guide to Equine Health Care. We at The Horse work to provide you with the latest and most reliable news and information on equine health, care, management, and welfare through our magazine and TheHorse.com. Your subscription helps The Horse continue to offer this vital resource to horse owners of all breeds, disciplines, and experience levels. To access current issues included in your subscription, please sign in to the Apple or Google apps OR click here for the desktop version.

Q. I have an ulcer-prone mare that I’ve always fed a forage-first diet with a vitamin supplement mixed with hay pellets. When I’ve fed concentrates in the past, she’s developed gastric ulcers. Now I’ve started training her for endurance and feel she needs more calories for this higher-intensity work. I’m curious about grain-free feeds for horses. What does grain-free mean? Does it mean low-starch? If they aren’t providing calories from grains, where is the energy coming from?

—Via e-mail

A. The Association of American Feed Control Officials defines grain as seed from cereal plants. For example, oats, barley, corn, and wheat—in their intact forms—would be classified as grains as they are all seeds from the respective plants. Wheat middlings, however, would not be classified as a grain as it is not the whole seed. Rather, “middlings” is specifically a term used to describe “a by-product of flour milling comprising several grades of granular particles containing different proportions of endosperm, bran, (and) germ, each of which contains different levels of crude fiber.”

Therefore, a feed could be labeled as grain-free (not containing the whole seed) but still contain ingredients derived from grain parts, such as wheat middlings. Removing whole grains from feeds typically results in a significant reduction in starch, and ingredients such as wheat middlings have become popular because these ingredients contain less starch than the entire grain but provide similar calorie levels. This enables feed manufactures to provide feeds with the higher calories for performance horses while controlling starch intake.

Ingredients such as wheat middlings are not, however, starch-free and, while grain-free feeds typically have lower starch contents, they might not be as low as necessary for some horses, especially those with metabolic issues. Therefore, it is always important to find out a feed’s non-structural carbohydrate (NSC) content if this is an important consideration for your horse, even when its labeled grain-free.

Other common ingredients used in grain-free diets to increase the feed’s calorie level include fermentable fibers, such as sugar beet pulp and soy bean hulls, as well as fat sources such as rice bran and vegetable oil. These would be good choices of fuel for a horse participating in endurance as they support the type of aerobic exercise endurance horses typically perform.

Of course, rice bran and sugar beet pulp can be fed very successfully on their own. However, a good vitamin/mineral supplement would be necessary to ensure the diet is meeting all your mare’s nutrient needs, especially trace mineral and vitamin E. A commercial grain-free feed has been properly fortified so, when fed correctly according to the manufacturer’s recommended feeding rates, you won’t have to supply any further vitamin or mineral supplements.

You’re right that veterinarians and nutritionists generally recommend reducing the amount of high-starch grain fed to ulcer-prone horses. Still, some level of starch in the diet can be beneficial for hard-working horses. The key is to only feed small amounts at a time, stretch high-starch meals out throughout the day, and not feed more than 1 gram of NSC per kilogram of body weight per meal per day.

Q: My pleasure horse is currently on antibiotics due to a wound he sustained in the pasture. Do I need to be concerned about him developing gastric ulcers from being on this course of antibiotics? What, if anything, can I do to combat the development of ulcers?

A: The judicial use of systemic antibiotic administration is often a critical component of successfully treating bacterial infections in horses. Along with the substantial benefits however, there are also potential adverse effects of antibiotic therapy. Diarrhea/colitis are likely the most common of these side effects, but kidney, liver, and neurologic effects, along with several other rare reactions, may be encountered. Conversely, there is no published evidence that administration of antibiotics in horses is associated with development of equine gastric ulcer syndrome (EGUS) in either form, equine squamous gastric disease, or equine glandular gastric disease. When administering antibiotics to horses, always follow your veterinarians’ instructions to minimize the risk of adverse effects.

Consideration of EGUS development in this situation is important. A horse being treated for a wound may experience feeding, housing, and management changes as well as increased stress, all of which are known factors associated with the development of EGUS. Combating the development of ulcers is closely tied to two things—managing how we feed our horses and alleviating stress in our horses’ lives.

In their natural state horses graze the majority of the day, producing large amounts of saliva and taking in enough grass to help protect the upper, acid-sensitive portion of the stomach from acid. Because a horse’s stomach produces acidic gastric fluid continuously, and in quantities of up to 16 gallons per day, the salivary buffering and physical protection is important to maintaining a healthy digestive system. When we practice episodic feeding with “dried” roughage and/or concentrated feeds, we interrupt the natural ability of the horse to buffer acid in the upper portion of the stomach. Providing access to grazing, hay in slow feeder nets or bins, and feeding small concentrate meals throughout the day are recommendations to decrease ulcer development risks.

Another way to help prevent ulcers is to reduce stress as much as possible. Many horse owners think it’s only the big events, like showing, trailering, or moving to a new barn that can trigger stress, but that’s not the case. Even what we might consider small things, such as storms, changes in feeding times, moving to a different pasture, or changing a turnout buddy, can also lead to stress, which can lead to the development of ulcers. Sticking to a routine as much as possible with our horses’ work, training, feeding, and turnout schedules can help. Horse owners can also download Relax Trax, a music soundtrack developed by an animal sound behaviorist specifically for horses. It’s available for free here. Consult your veterinarian if you think an approved gastric ulcer prevention could be beneficial to your horse’s circumstance.

Equine gastric ulcer syndrome (EGUS) is a common disease in horses, frequently treated with the proton-pump inhibitor omeprazole to decrease stomach acidity. Some horses being treated with omeprazole, however, suffer rapid recurrence of gastric ulcers upon discontinuing treatment. Tapering the omeprazole dose when planning to discontinue this medication is unlikely to minimize rebound gastric hyperacidity. Instead, caretakers can implement management changes to further protect the horse from developing new lesions.

“EGUS is an umbrella term that refers to horses with lesions in either the squamous (upper) or glandular (lower) regions of the stomach,” said Pamela A. Wilkins, DVM, MS, PhD, Dipl. ACVIM, ACVECC, Veterinary Clinical Medicine Section Head and professor of equine medicine and surgery at the University of Illinois’ College of Veterinary Medicine, in Urbana-Champaign. “Each is actually a separate disease with its own risk factors, but both are essentially a result of damage caused by acid in the stomach.”

Squamous ulcers often occur because of exposure to acidic gastric juices, typically during periods of fasting or intense exercise. “In contrast, glandular disease is believed to result from breakdown of normal mucosal defense mechanisms with gastric acid perpetuating the injury,” Wilkins explained.

In both cases, gastric acidity is the common denominator, making acid suppression key to medical management.  

“Omeprazole is a proton-pump inhibitor that suppresses gastric acid secretion to decrease the acidity (i.e., increase the pH) of the gastric juices,” she said.

Veterinarians prescribe omeprazole to treat gastric ulcers, both squamous and glandular. But, according to a recent study, squamous ulcers can recur to pretreatment levels in as little as three days following discontinuation of treatment. 

“This phenomenon is thought to be due to ‘rebound gastric hyperacidity’ secondary to abnormally high levels of the hormone gastrin,” relayed Ben Sykes, BSc, BVMS, MS, MBA, Dipl. ACVIM, PhD, FHEA, gastrointestinal ​disease researcher and professor at Southern Cross University, in New South Wales, Australia.

Gastrin stimulates hydrochloric acid production in the stomach. Under normal conditions, when pH levels decrease (i.e., the stomach becomes more acidic), gastrin is inhibited. When the stomach pH levels increase, more gastrin is produced, which in turn stimulates increased acid output. Omeprazole interferes with this normal feedback loop between gastrin and gastric pH.

“As a result, circulating gastrin levels become elevated in human patients treated with omeprazole, which means that when omeprazole is discontinued, those high gastrin levels immediate stimulate the production of excessive hydrochloric acid, thus rebound gastric hyperacidity,” Sykes explained.

High gastrin levels also cause growth of other cells called enterochromaffin-like (ECL) cells, which are important in signaling for gastric acid production. Increased ECL cell density might also contribute to rebound gastric hyperacidity.

To determine if gastrin levels and ECL cells increase with omeprazole therapy, Sykes’ research team recruited 14 retired Thoroughbred racehorses used for training. Those horses received 2.28 grams (approximately 4.4-5.3 mg/kg) of omeprazole orally, once daily at 4 a.m., 30 minutes prior to being fed, for 57 days. The research team measured the horses’ gastrin levels at baseline, weekly throughout the treatment period, and weekly for one month following cessation of therapy. They measured ECL cell density by assessing serum chromogranin A (CgA) levels.

“As we hypothesized, gastrin levels more than doubled within seven days of starting omeprazole,” said Sykes. “However, gastrin decreased back to normal levels within two days of stopping therapy. This was somewhat surprising because much longer persistence has been reported in humans.”

These results indicate a loss of feedback on gastrin production with omeprazole; however, the increased gastrin concentrations did not persist when omeprazole was discontinued. Therefore, the researchers did not believe the gastrin levels contributed to rebound gastric hyperacidity beyond the immediate post-treatment period. 

ECL cell density did not increase during or after treatment, suggesting these important signaling cells also do not contribute to rebound gastric hyperacidity.

“Recurrence of gastric ulcers following cessation of omeprazole still occurs, and rebound gastric hyperacidity might still play a role, but the effect is very short-lived,” said Sykes. “As such, the use of tapering protocols for omeprazole, which are widely used in human medicine and have commonly been adopted in equine medicine, are not justified in the horse—at least for treatment durations of eight weeks and less.”

Instead of tapering omeprazole when discontinuing the medication, Sykes said horse owners should focus on optimizing preventive management practices and removing risk factors during the immediate post-treatment period.

This includes providing adequate roughage, ideally including alfalfa hay, and complete rest during the 48 hours following the last dose of omeprazole. Caretakers should then focus disease prevention primarily on long-term management.

Wilkins offered the following management recommendations:

• Decreasing exercise intensity and frequency, if possible.
• Providing free-choice roughage during the day.
• Offering alfalfa for its inherent buffering capacity.
• Allowing horses access to turnout, if possible.
• Limiting non-steroidal anti-inflammatory drugs (NSAIDs), restricting their use to only when necessary.

“NSAIDs are known to promote EGUS,” added Wilkins. “This class of drugs includes the commonly used medications Bute (phenylbutazone)and Banamine (flunixin meglumine). Further, fasting horses should be limited, particularly if NSAIDs are being used.”   

“I’m really excited about the potential impact of this research,” Sykes said. “Removing the need for tapering of omeprazole following short- and medium-term therapy has the potential to save owners hundreds of dollars in unnecessary treatment while focusing prevention efforts on the highest risk period immediately post-treatment.”

He said his team hopes to extend their research to horses treated for longer periods to determine if the same recommendation can be made for those groups, as well.

The study, “Evaluation of the effects of medium-term (57-day) omeprazole administration and of omeprazole discontinuation on serum gastrin and serum chromogranin A concentrations in horses,” was published in the Journal of Veterinary Internal Medicine in August 2023.

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Your show horse is a marvel of athleticism, bred and trained to perform incredible feats. But like any athlete, his joints and soft tissues sustain wear and tear with use, especially if you don’t care for them properly. Routine preventive care is the best medicine for extending the life span of your horse’s moving parts. From dental and hoof care, vaccination, and deworming to comprehensive joint therapy and pre- and post-exercise stretching, being deliberate about preventing problems ultimately enhances your horses’ well-being, long-term health, and performance.

One organ system that is particularly sensitive to the trials of competition is the gastrointestinal tract. Here are three aspects of the GI tract that can negatively affect a show horse’s performance and quality of life if not managed appropriately.

Click the link above to download your free copy of this special report.

]]> https://thehorse.com/1121773/managing-ulcers-in-the-competition-horse/feed/ 0 https://thehorse.com/136769/feeding-young-horses-graduating-to-a-grown-up-diet/ https://thehorse.com/136769/feeding-young-horses-graduating-to-a-grown-up-diet/#respond Sat, 25 Feb 2023 16:00:00 +0000 https://thehorse.com/36769/feeding-young-horses-graduating-to-a-grown-up-diet/ Consider growth rate and nutrient balance when deciding what to feed young horses.]]>