Enteroliths are a type of foreign body that can be found in horses’ intestines and are one possible cause of colic, or abdominal pain. Unlike sand or gravel, which horses ingest when they are grazing or eating outside, enteroliths develop when mineral deposits form in concentric layers around a central nidus, such as a piece of wire, small stone, twine, etc., in the large colon (the stretch of intestine between the cecum and the transverse colon). Horses can either have one enterolith (usually round and large) or multiple (often tetrahedral in shape, meaning they have angles or corners).

What Causes Enteroliths?

The cause behind enteroliths—and, especially, why some horses develop them but not others—is still not fully understood. Feeding high levels of alfalfa hay, particularly in California or other locations out west, has been associated with enterolith formation. Decreased turnout and limited access to pasture also have been linked to their development, possibly because of decreased intestinal motility or increased ingestion of alfalfa when stalled. Certain horse breeds (Arabians, Morgan horses, American Miniature horses, and Saddlebreds) have been shown to be more at risk for forming enteroliths.

Enteroliths cause problems when they get large enough that they begin to pass into the transverse or small colon. The diameter of the transverse and small colon is much smaller than the adjacent large colon, so the enteroliths become wedged. Once wedged they block food and gas from traveling out of the intestine, causing abdominal pain and signs of colic.

Some horses with enteroliths could have a history of recurrent colic (repeated colic episodes) due to enteroliths intermittently blocking the intestine and then other times allowing food and gas to pass normally. When the enterolith becomes completely wedged the horse will show signs of severe colic due to gas distension. If the enterolith is large enough and puts pressure on the intestine, it can cause necrosis of the intestinal wall in that area and lead to leakage of feces into the abdomen and secondary infection. In these cases horses show lethargy, decreased appetite, and fever, eventually progressing to signs of sepsis (a life-threatening systemic inflammatory response to infection) and shock. Due to how firmly enteroliths become lodged in the intestines, the treatment for enteroliths is always surgery.

Diagnosis

Veterinarians usually diagnose enteroliths at the time of colic surgery, when the colic signs do not respond to medical treatment, and/or the horse’s colon becomes distended with gas due to blockage by the enterolith. Abdominal X rays can be performed, but in most cases enteroliths are hidden by the large amount of tissue in the horse’s abdomen, making them difficult to detect.

Prevention

If your horse has had enteroliths before, veterinarians recommend taking preventive measures, because there is some evidence they can form again. In these cases, avoid feeding alfalfa and provide as much turnout on pasture as possible.

If at any point you see what looks like an enterolith in your horse’s manure, tell your veterinarian, because the presence of one enterolith (especially if it has a tetrahedral shape) often means there are more in your horse’s intestines. And if your horse shows signs of colic, you should always contact your veterinarian immediately.

Postpartum mares face a higher risk of developing large colon volvulus—a life-threatening type of colic in which the colon twists 360 degrees or more, cutting off blood flow and blocking the passage of gas and feed. Jesse Tyma, DVM, Dip. ACVS, a surgeon at Rhinebeck Equine, in New York, described the diagnostic and treatment approaches to this condition at the 2025 Cavalcade Education Equine Reproduction Seminar, held in Red Hook, New York, on Jan. 8.

Anatomy and Susceptibility in Postpartum Mares

Tyma described the large colon as a partially mobile gastrointestinal organ prone to displacement and twisting within the horse’s abdomen. The reason postpartum mares are especially susceptible to this condition relates to the empty space left in the abdomen after foaling, which allows the colon to shift more easily.

Diagnosing Large Colon Volvulus in Mares

The clinical signs of colic in a mare with large colon volvulus are usually severe, including vigorous pawing, violent rolling, a bloated appearance, and intractable discomfort. Tyma emphasized that prompt diagnosis and treatment are critical to the mare’s survival and foal’s safety.

“The colic exam aims to assess the postpartum mare’s overall health status, localize the lesion, and differentiate between a volvulus involving ischemia (lack of blood flow leading to oxygen deprivation and tissue death) and a displacement or other type of colic where the blood supply is unaffected,” said Tyma. “Diagnostics may include palpation per rectum, passing a nasogastric tube to check for gastric reflux, abdominal ultrasound to evaluate the colon wall and vasculature positioning, and bloodwork to measure lactate levels (which can signal severe tissue damage and the need for urgent intervention) and assess overall systemic health.”

Tyma also stressed the need to carefully assess the reproductive tract in the immediate postpartum colicky mare to rule out life-threatening hemorrhage, the clinical signs of which can overlap with those of large colon volvulus.

Treating Large Colon Volvulus in Mares

If a veterinarian strongly suspects large colon volvulus, the mare will likely need emergency colic surgery. “The goals of surgery are to characterize the lesion, manually correct the volvulus, and assess bowel viability to guide surgery decisions,” said Tyma. The surgeon might also perform a colon resection (the damaged tissue can be removed, and the healthy ends of the intestine stitched back together) or colopexy (creating an adhesion to the body wall to prevent future displacements and torsions), she added.

Postoperative Care and Complications

Beyond the risks of surgery and general anesthesia, recovery from large colon volvulus surgery involves intensive care because these mares often become systemically compromised and can decline quickly. “The postoperative patient requires close monitoring with serial examinations, multimodal pain management, fluid therapy, broad-spectrum antimicrobials, digital cryotherapy (icing the legs), supportive care, and a gradual reintroduction of feed,” Tyma said.

She added that common postoperative complications can include endotoxemia (toxin release into the bloodstream), diarrhea, recurrent colic, surgical site infection, and the painful hoof condition laminitis. “Transitioning the accompanying foal to a nurse mare is often recommended to lessen the physiologic demand on mares early in the postpartum period.”

Prognosis for Large Colon Volvulus in Mares

“In the best of clinical scenarios, the short-term prognosis for large colon volvulus is excellent, with survival rates reported up to 90%,” Tyma said. “However, in studies representing a broad population with variable referral access (to a surgical facility), the short-term survival rate is just 71%, with long term survival dropping to less than 50% by one year postoperatively. This speaks to the importance of quick referral and management for successful outcomes.”

Sixty-seven percent of mares treated for large colon volvulus produce at least one foal postoperatively. “The risk of recurrence of large colon malposition (inclusive of both surgical correction of displacement and volvulus) is 15%, and, following two occurrences of volvulus, the recurrence rate jumps to 80%, which is significant,” Tyma said. “Mares with recurrent volvulus that are intended to continue as broodmares should be considered candidates for a prophylactic procedure (colopexy or large colon resection) to reduce the risk of recurrence.”

Take-Home Message

Large colon volvulus presents a true emergency in postpartum mares, demanding rapid diagnosis, aggressive treatment, and intensive postoperative care. Tyma emphasized the importance of prompt referral to a surgical facility and potentially prophylactic procedures such as colon resection or colopexy in high-risk mares to reduce the risk of recurrence. “Prognoses for survival and continuation of reproductive careers can be good to excellent but remain dependent upon quick recognition of the condition, immediate action, and appropriate surgical and postoperative management,” she said.

Q: I’ve always enjoyed giving my horse a warm bran mash in cold weather, but this doesn’t seem to be something people do much anymore. Is there still a place for wheat bran in my feed room?

A: Growing up I routinely fed a warm bran mash to my horse in the winter, especially on days when he worked hard. However it’s far more unusual now in part because we’ve realized that it might not be as beneficial as we once believed.

In my 1983 8^th Edition of the British Horse Society and The Pony Club Manual of Horsemanship it states that a bran mash is a “very useful warm food after hard exercise and hunting.” It goes on to say that after adding boiling water to the bran, you should add a generous amount of salt along with some oats, and then feed once cool. It finishes by saying “bran mash has a laxative value, and it has everything to recommend it when fed once a week to horses in work and to invalid horses. It is also a convenient way to administer medicines such as worming compounds.”

So how did a feed and feeding practice that were once so popular fall out of favor? To better understand that you need to understand your horse’s digestive tract, as well as the composition of the feed.

About Diet Changes and Digestive Tract Upset

Most of us are well aware that changes to a horse’s diet should be made gradually over several days. The reason for this is that the digestive enzymes, the amount secreted as well as the bacteria in the horse’s hind gut, are somewhat specific to the diet being fed. Therefore, if you change the makeup of the diet the enzymes and digestive bacteria must adapt, and this takes time. In the meantime if too much new feed is fed the horse might not be able to fully digest it and can lead to digestive disturbance (e.g., diarrhea, gas, and colic, etc.).

As previously mentioned, horse people used to routinely feed bran mashes once a week, largely for their believed laxative effect. Since becoming more educated in equine nutrition, it’s fascinated me that—while we take great care not to suddenly change a horse’s diet when starting most new feeds—this logic goes out the window when it comes to a bran mash. Essentially, when you feed a bran mash once a week you’re breaking all the guidelines you typically follow in keeping your horse’s diet consistent. The “laxative effect” might be because the feed change is causing digestive distress! This is probably not the best method of ensuring your horse’s digestive contents stay on the move.

Wheat Bran’s Nutritional Imbalance

Wheat bran has also fallen out of favor because of its high phosphorus level. In fact wheat bran has an inverted calcium to phosphorus ratio, meaning that it contains more phosphorus than calcium. This is actually common in traditional grains such as wheat, oats, and barley. However, wheat bran is particularly high with a phosphorus content of about 1% and calcium at only 0.15%.

Researchers realized feeding diets with a lot of wheat bran increased the risk of developing secondary hyperparathyroidism, a condition that results from a calcium imbalance potentially caused by horses consuming a diet too high in phosphorus. “Big head” or “bran disease” was far more common when horse owners and managers fed traditional grains and wheat bran more commonly than we do today. In reality this condition is unlikely to result from feeding a bran mash once a week. It’s far more likely if bran or traditional grains are fed daily in a poorly balanced ration. Traditionally any number of unfortified grains could have caused a similar issue, but because, proportionally, brans add much more phosphorus per pound than the grains, they are often considered a larger problem. With the concern over big head and potential links to bran, much less wheat bran is now fed and most rice brans are fortified with additional calcium carbonate to neutralize the problem.

So, What’s Right About Bran?

Going back to the quote from my Manual of Horsemanship, if a bran mash has “everything to recommend it,” what’s it doing right, given the two already discussed areas of concern? First, the manual hints that bran mashes are generally welcomed by even the most picky eater. Often, after very long and heavy work such as fox hunting, horses might have a reduced appetite and the goal is to get the horse eating and the digestive tract moving. Some sick horses that have gone off feed can be tempted to eat with a bran mash. Therefore, a bran mash can be a very useful tool when faced with a horse that has gone off feed and will not eat anything else.

Second, adding salt to a bran mash is a great practice, especially when fed after work that might have incurred heavy sweat losses.

Alternative Warm Mashes for Your Horse

So, when you want to give a bran mash is there something else that might be more beneficial? Is there a better way?

If you already give your horse supplemental feed, whether it is pellets or a textured feed, add hot water to make a warm mash just as you would with wheat bran. This way you are creating the mash but using familiar feeds that are less likely to irritate the gastrointestinal tract.

If you only feed forage, purchase some hay pellets that are like the forage you feed and use them to make a mash.

Next add some salt, or if you already give salt every day and your horse has been sweating heavily, add an electrolyte. If you need to entice a picky eater or a horse that has gone off feed, try adding carrot or apple peelings. If you have your heart set on a weekly bran mash, then I suggest adding a small amount of bran to your horse’s every day feed so that the mash is not a novel feed to your horse’ digestive tract. But be careful to keep the amount of bran small and consider discussing with an equine nutritionist how to add bran to your ration while maintaining a balanced mineral profile.

Q: I’ve always heard horses are more prone to impaction colic during winter, especially if they don’t drink enough water. Is this true? If so, what can I do to reduce my horse’s risk of impaction colic this winter?

A: At its most basic, colic is a term covering a wide variety of abdominal pain and can occur throughout the year. Impaction colic describes an incidence of colic related to a large bolus of feedstuffs or waste being caught (impacted) within the intestines. Impaction colic during the colder months is commonly associated with two dietary changes: an increase in the amount of dry feed consumed (especially hay) and a decrease in water intake.

A quick way to determine if your horse is consuming enough water is to routinely monitor his feces. If you notice dry, hard, and crumbly fecal balls, he is not drinking enough.

What Horses Are Prone to Impaction Colic During Winter?

Not all horses develop impaction colic during winter. Owners and managers can decrease their horses’ potential for the condition by monitoring diets, especially forage quality, water intake, and making sure fresh water is always available.

Horses evolved as animals that spend a significant amount of their time walking around and consuming forage. This almost constant movement helps keep the digestive tract moving feedstuffs and waste through, so we should make sure our horses get exercise. When storms or weather extremes arrive, we often believe putting our horses in stalls is in their best interest. However, researchers have shown equine gut motility significantly decreases the first few days after a horse moves inside for stall confinement, which can lead to an increase in impaction colic risk.

Improving Water Intake to Reduced Risk of Impaction Colic

The average adult horse consumes approximately 1 gallon of water per 100 pounds of body weight, or approximately 10 gallons if he’s a 1,000-pound horse. Horses need water for proper digestion and movement of feedstuffs through the digestive tract; the drier the feed provided, the more water the horse needs for the digestive tract to function properly.

In colder months, be certain your horse has water available that is not frozen. Some horses are willing to break a layer of ice if it forms on top of the water source, while others are more reluctant. Check your horse’s water sources several times each day to ensure they have not frozen. If your horse doesn’t want to drink very cold water, consider adding warm water (even from a thermos if you don’t have hot water in your barn) to bring up the water temperature in his buckets. You can also find ways to insulate buckets to help keep water from freezing if you cannot use heated buckets or trough heaters.

Top dressing either concentrate or flakes of hay with some loose table salt or other electrolytes can encourage a horse to drink. Soaking his feed and making a mash or slurry also incorporates more water into his diet. Although horse owners have historically used bran mashes, suddenly providing a feed like this can cause digestive upset or unbalance the diet. Now researchers discourage owners from feeding a true bran mash.

Take-Home Message

Keeping your horse hydrated is a key step to limiting his risk of impaction colic. Make sure the water you provide him is palatable and not frozen and be sure he has exercise opportunities to improve gut motility. Finally, check his hydration status daily to ensure he consumes enough water.

Do you have an equine nutrition question?

Diseases of the small intestine account for approximately 34% of all colic cases treated at veterinary hospitals. Most (up to 85%) are caused by strangulations, which disrupt blood supply to the small intestine. The most common small intestinal strangulating diseases in adult horses are caused by pedunculated lipomas.

What is a Pedunculated Lipoma?

A pedunculated lipoma starts as a discrete plaque of fat within the mesentery of the small intestine. The mesentery is a broad but thin sheet of tissue that attaches the small intestine to the roof of the abdominal cavity and contains the critical arteries that provide life-sustaining oxygen to support normal intestinal function. As the horse gets older, the lipoma progressively enlarges and thereby stretches its attachment to the mesentery to form a long cordlike structure called a pedicle. The pedicle then wraps around a segment of nearby small intestine and its mesentery like a South American bola to strangulate these tissues until they die.

Lipoma development takes time, which explains why most affected horses are 10 years and older at the time of diagnosis. Old age is therefore an immediately recognizable diagnostic clue to strangulating lipoma. Unfortunately, affected horses are also victims of a diagnostic distraction: their own stoic attitude that blunts development of the more severe signs of colic.

One of the most dramatic observations in these cases is how the intestinal injury severity identified at surgery can exceed the vet’s expectations based on the preoperative condition and attitude of the horse. The only colic-related clues an owner picks up on might be a depressed attitude and abrasions about the head. Don’t ignore these abrasions, because they indicate the horse was rolling with sufficient intensity to rub his head repeatedly against the ground. If the horse is no longer rolling or showing other signs of pain, he has reached a state of shock and exhaustion.

Timely Intervention and Treatment

The lack of clear signs of colic means too many of these horses are treated at home, using a “watch-and-wait approach” and even given intravenous fluids to combat dehydration. All this does is delay the inevitable referral to a hospital for possible surgery. The delay can be not only fatal but also very expensive because it creates the need for a complicated surgery and intensive aftercare, both of which would be unnecessary if the horse were to go to surgery promptly to avoid resection of dead intestine. In fact, results from a recent study showed superior short- and long-term survival (up to 20 years) in horses that did not need removal of strangulated small intestine compared with those that had more advanced changes and needed removal by resection and anastomosis (joining the resected ends).

Unfortunately, the watch-and-wait approach is very attractive when horses have “manageable” signs of colic and their owners have financial constraints or doubt the benefits of surgery. Also, owners must consider many factors when selecting the surgical option, such as how many more years the horse will live—especially if he is nearing the end of a reasonable life span—and if he can continue to perform after surgery. Your horse might have other health problems unrelated to colic, making it time to say goodbye.

Delaying this decision can carry a high price and should not be justified by myths such as “the horse will never be the same” or “colic surgery does not work.” Some owners allow themselves to be lulled into the belief that if the pain is manageable, they can “kick the can down the road,” treat the horse at home, and pursue surgery if absolutely necessary. Surgery is by that point too late and far more expensive than if it had been done earlier.

Lipoma is not the only cause of colic in old horses, but it is the most common, which means if you own an older horse, consider how far you are prepared to go financially to save his life. Make this decision when the horse is healthy and free of life-threatening disease. Above all, be guided by the maxim that “an old horse with colic has a strangulating lipoma until proven otherwise.”

Q: I have a 28-year-old gelding who suffered an impaction colic last week. We’re not really sure why it happened, because nothing has changed in how he is managed. What can I do to help prevent it from happening again?

A: Colic is scary to witness, and not knowing the cause can be very stressful. Of course we all want to make sure it doesn’t happen again. Assuming there’s no physical cause for impaction, such as a tumor, which can occur in older horses, common causes include dehydration and poorly digested feed. Therefore, avoiding dehydration and improving digestion are key.

Salt and Hydration

Ensuring your horse is consuming enough water is necessary for avoiding dehydration. Sodium intake each day helps stimulate water consumption, so make sure your horse gets enough salt each day. Many owners rely on salt blocks to provide their horses with a sodium source, but few horses adequately utilize salt blocks.

An average 1,100-pound horse must consume about an ounce of sodium chloride a day to meet maintenance sodium requirements. This would be equivalent to consuming 2 pounds of salt in block form each month. Few horses achieve this intake from blocks. Therefore, I like to feed horses an ounce of salt (which is 2 tablespoons) each day and then provide them access to a plain white salt block, as well. If the weather is hotter, then you can give additional salt or an electrolyte supplement. If your horse does not like the taste of salt, then you can use an electrolyte instead, because sometimes electrolytes are more palatable than straight salt.

Salt consumption should stimulate thirst and encourage your horse to drink. Make sure water is easily accessible. If older horses have joint pain they might be less willing to walk distances to get to water, so consider having several water sources available. When feeding hay, you might find your horse drinks more if water is near his hay.

Soaking Hay

That said, soaking hay is an effective management strategy for horses prone to impaction colic. First, it increases water intake without the need for drinking more water, and secondly it softens the hay and makes it easier to chew. Keep in mind that horses fed soaked hay might not consume as much water from other sources, such as buckets or troughs, so it might initially appear that your horse is consuming less water.

Even if senior horses have healthy teeth, they might not have as much strength in their jaws to grind and chew hay as when they were younger. Inadequately chewed hay creates a greater impaction risk. Soaking hay to make it softer can be beneficial. Feeding softer, less stemmy hays might also help, because they tend to be more easily digestible. Senior horses that can graze pasture grass safely might have a reduced impaction risk when grazing, because fresh grass contains more water and is softer and easier to chew than hay.

Pellets Instead of Hay

For some horses, feeding hay pellets might be a better option than long-stem hay. Once chewed, pellets have very small particle sizes, which reduces impaction colic risk. If desired, you can feed pellets soaked. In fact, you can prepare any textured or pelleted feed as a mash or soup as a way of increasing water consumption.

Hindgut Health

In addition to making sure your horse consumes enough water and chews his forage properly, supporting forage digestion might be beneficial. Research shows supplemental live yeast can help improve organic matter utilization in the hindgut. This improvement in forage fermentation might help reduce the risk of hindgut impaction.

Exercise

Finally, make sure your horse is getting adequate exercise, as movement aids digestion. Senior horses tend to move less due to joint pain or because they have been retired from riding. Have your veterinarian look over your horse and provide him with support for any joint discomfort. If your horse isn’t turned out, consider at least hand-walking or longing him each day.

Take-Home Message

By implementing some of these recommendations and practicing overall careful management you can potentially limit your older horse’s risk of a repeat impaction colic episode.

Time is of the essence when dealing with colic—the broad term for abdominal pain—in horses. Colic is a leading cause of death in equids and, in a new study, U.K. researchers found the survival of colicking horses depends heavily on rapid decision-making from veterinarians and horse owners.

Gathering Information from Decision Makers

To collect data from the people most directly involved in managing colicking horses, researchers from the University of Nottingham’s School of Veterinary Medicine and Science conducted phone interviews with 14 horse owners and 13 veterinarians across the U.K. They centered the discussions on experiences with critical colic cases—those severe enough to involve hospital referral or euthanasia. The questions explored diagnosis, treatment options, and the emotional challenges of decision-making.

Researchers found several prominent themes across the responses:

• Emotional impact: Both horse owners and veterinarians experienced significant emotional stress surrounding decision-making, influenced by the severity of the colic, the uncertainty of the outcome, and the bond between horse and owner.
• Owner preparedness: Veterinarians reported that many owners had never considered what they would do if their horse were critically ill. Even those who had thought about decisions in advance often became conflicted during an emergency.
• Information and resources: Owners reported varying levels of access to information about colic management and treatment options for their horses. Some felt inadequately informed, others appreciated detailed explanations from their veterinarians.
• Financial considerations: While finances were a concern for owners, they overwhelmingly did not consider money the most important factor when deciding on colic treatment. In contrast, veterinarians saw cost as one of the biggest influences on decision-making, especially when survival depended on urgent referral. The researchers said that having equine insurance reduced owners’ anxiety, making them less concerned about discussing costs and taking action on procedures.
• Logistics and travel considerations: Researchers noted that logistics and availability of horse transportation to a hospital were a common source of anxiety for both veterinarians and owners. Practitioners frequently reported transport-related issues, including owners not having access to suitable transport when needed and horses that were difficult to load.

What an Emergency Equine Colic Means for the Client-Veterinarian Relationship

“The long-term impact a critical colic case has on a horse owner can be profound, with feelings of intense guilt and changes in attitude to future horse ownership,” said study author Katie Burrell, BSc, PhD, assistant professor of equine welfare and knowledge exchange at the university.

To help with informed decision-making, Burrell and her colleagues called for increased resources and support for owners navigating the complexities of colic treatment decisions. “The REACT campaign is an initiative by the British Horse Society that provides owners with key information and guidance on preparing for a potential colic emergency,” she said. The REACT colic campaign includes a poster of the most common signs of colic, and ten fact sheets on colic essentials.

Take-Home Message

In cases of severe colic, minutes can make a difference. To improve the outcomes of critical colic cases, Burrell strongly encouraged horse owners to make and discuss emergency plans with their veterinarians and those directly involved in the horses’ care—such as barn owners and trusted friends—in advance to prevent delays should an emergency arise.

The study, “UK horse owners and veterinary practitioners’ experiences of decision-making for critical cases of colic,” appeared in Equine Veterinary Journal in June 2024.

As equine care has evolved, the proportion of senior horses—those 16 or older—within the population has grown. While transitioning your horse from a successful performance career to a well-deserved retirement can be straightforward and satisfying, medical decision-making can begin to feel more ­complicated during this stage. In two large studies gastrointestinal (GI) disease was the most common reason for admission to a referral hospital, with colic being the major cause.

Colic is stressful for any owner, especially when trying to decide whether to send a horse to colic surgery—a decision that can become more complex as your horse ages. To help you with this difficult choice, here are considerations to discuss with your veterinarian.

Colic Type

Colic falls into many categories. Here I’ll focus on small intestine vs. large intestine and strangulating (when something obstructs the blood supply to the tissue) vs. nonstrangulating. Of these distinctions, geriatric horses are at increased risk of a strangulating lesion of the small intestine (Krista et al., 2009). This is because geriatric horses are more likely to develop strangulating lipomas, which are essentially balls of fat with a stalk that ensnares a piece of the GI tract, than young adult horses. Unfortunately, horses with small intestine lesions have lower rates of survival to hospital discharge than those with large intestine lesions.

In one study, however, Southwood et al. found no significant difference between short-term survival rates of surgically managed geriatric and adult horses with small intestine strangulations. They did note that upon adding a subcategory of horses ages 20 or older, those surgically managed cases had lower short-term survival than the adult horses.

It appears that while geriatric patients are at higher risk of having a colic type with a more guarded prognosis, if taken to surgery they typically have similar short-term survival rates as adult horses undergoing surgery for the same lesion type.

Anesthesia

Anesthetizing any equine patient comes with risk. The size of horses, necessity for them to stand following the procedure, and critical status of some colic patients are just a few of the factors that can translate to equine anesthesia difficulties. In a 2020 study of 1,161 equine anesthesia cases Laurenza et al. found increasing age was a major risk factor for complications and/or mortality. Of those, neuromuscular, respiratory, and cardiovascular complications were associated with increasing age. Understanding the risk of anesthesia is prudent for any owner of a colic patient; however, you might want to discuss with your veterinarian any major contraindications he or she might expect with your horse.

Postoperative Healing

A surgical colic patient’s journey to a successful hospital discharge does not occur as soon as he or she is standing safely in recovery. The postoperative period is critical. Again, colicking geriatric patients are more likely to have strangulating lesions of the small intestine. These lesions are also associated with a postoperative complication known as reflux, where GI fluid accumulates and, instead of being expelled through reabsorption and defecation, fills the stomach and must be removed by nasogastric intubation.

In addition, a common disorder of geriatric horses is pituitary pars intermedia dysfunction (PPID, formerly equine Cushing’s disease). The alterations in PPID patients’ inflammatory and immune responses might create difficulties in the postoperative healing period. Therefore, it is important to understand that geriatric surgical colic patients might require more supportive care postoperatively.

Financial Burden

The financial burden of colic surgery is a reality for most horse owners, because the associated costs have increased (Blikslager et al., 2020). While insurance policies cover a portion of the equine population, an owner might be less likely to insure a geriatric horse. In addition, strangulating lesions of the small intestine have been associated with higher expenses compared to those for large intestine nonstrangulating lesions. The more intensive postoperative support small intestine lesions sometimes need can significantly impact total cost.

While each case differs, geriatric horses can respond as well to colic surgery as adult horses with similar lesions. As with surgical colic of any aged horse, discuss the lesion type, possible anesthetic and postoperative complications, and financial impact with your veterinarian.

Late-gestation abdominal pain in mares can be a perplexing enigma, a blend of mystery and urgency

A horse of any sex or reproductive status could experience abdominal pain from gastrointestinal (GI) distress or muscle pain in the abdomen. But a pregnant mare showing abdominal discomfort could be aborting her fetus or developing pregnancy complications.

Most colics resolve uneventfully: no surgery or even fluids needed. “Abdominal pain is common in horses in general,” notes Ashley VanderBroek, DVM, Dipl. ACVS-LA, assistant professor of large animal surgery at Michigan State University (MSU) College of Veterinary Medicine, in East Lansing.

When it comes to dealing with pregnant mares, “I would say the majority of colic cases are similar to horses that are not pregnant—usually mild and resolve on their own,” VanderBroek says. However, when a pregnant mare’s colic becomes severe, it might require “prompt surgical management.”

Causes of Late-Gestation Colic

“Colic is just a term to describe abdominal pain in the horse,” VanderBroek explains. “Most of the time that’s associated with the GI tract, but it doesn’t have to be.”

“We have to think about the GI tract, urinary tract, and reproductive tract when a horse is displaying signs of colic,” adds Julie Strachota, DVM, MS, Dipl. ACT, assistant professor and director of clinical education at MSU’s College of Veterinary Medicine.

In late gestation space is scarce in the abdomen. So, in a pregnant mare experiencing abdominal pain, “some of it could just be discomfort from everything being a little bit more compressed,” VanderBroek says.

When the mare’s internal organs get compressed and displaced, diagnostics become challenging.

“It is very, very hard to call some of these ‘GI problems’ just based on palpation or based on ultrasonography,” says Ahmed Tibary, DMV, MS, DSc, PhD, Dipl. ACT, professor emeritus in the Department of Veterinary Clinical Sciences at Washington State University College of Veterinary Medicine, in Pullman.

With abdominal distress veterinarians often discern first whether surgery will be necessary. The precise diagnosis comes later.

Gastrointestinal Colic

Notable GI colic types in pregnant mares include a large colon volvulus (rotation of the bowel), cramping from gas, and impactions in or displacements of the large colon.

A large colon volvulus occurs when the colon rotates and tightly twists around on itself, VanderBroek explains. It is more commonly seen immediately post partum. “That is the most fatal form of colic, and broodmares, particularly, are predisposed to that.

“They are violently painful, like intractable pain,” she says. Getting close enough to administer sedatives safely can be difficult.

Sometimes the colic is just gas.

“Gas is produced during digestion, so the colon needs to be able to expand,” VanderBroek says. But when there’s a “big gravid uterus,” a little gas can lead to discomfort more quickly.

“Of the GI causes (of colic in late-gestation broodmares) approximately half are medical,” meaning they can be treated without surgery, says Julie Dechant, DVM, MS, Dipl. ACVS and ACVECC, professor of clinical equine surgical emergency and critical care at the University of California, Davis, School of Veterinary Medicine. “Of those needing surgery, almost 80% are strangulating lesions.” Those are mostly found in the large intestine.

Pregnancy-Related Colic

Notable pregnancy-related colic includes uterine torsion, abortions or dystocias (difficult births), hydrops (fetal fluid accumulation in the uterus), tearing of the abdominal wall, and uterine artery bleeding.

“Uterine torsion and uterine artery bleeding each account for approximately 5% of late-gestation colic,” Dechant says.

Uterine Torsion occurs when the mare’s uterus twists on its axis, potentially cutting off blood supply and damaging the placenta. It occurs more frequently during the final three months of gestation, Strachota says.

 Veterinarians diagnose uterine torsion using transrectal palpation, which they use to check the severity and direction of the twist, Tibary says.

Mares with uterine torsions usually display mild to moderate abdominal discomfort, Strachota says. They might lie down more, have a decreased appetite, or defecate less than they should.

Cases of late-gestation mares showing signs of colic can present another issue: premature foals. These foals face such long odds that VanderBroek says she avoids delivering them early.

“If I take a mare to surgery for a uterine torsion, even if her due date is next week, I will correct the torsion, and I will leave the foal in the uterus,” VanderBroek says.

Abortion and parturition (giving birth) have similar clinical signs and can include vulvar discharge, relaxation of the prepubic tendon, and mammary development. Nesting in the stall, eating less, or isolating from other horses are other signs, Strachota says.

Dystocias can occur with live foals but are more likely if a fetus dies in the uterus.

“Horses have to be born a specific way,” with head and legs extended, VanderBroek explains. If the head or legs are bent instead of in a “forward dive” position, the mare might have difficulty delivering.

Hydrops is rare but “one of the most critical as far as emergencies,” Tibary says. Hydrops occurs when an abnormally large amount of fetal fluid accumulates in the mare’s uterus.

“The last case I had was 230 liters of fluid,” Tibary says. “That’s 230 liters pressing on the diaphragm.”

Respiratory distress can be a sign of hy- drops, he says, or they are a downer mare—one that is lying down and unable to rise.

Muscle Tone and Age can contribute to colic risk, with aging mares or those with pituitary pars intermedia dysfunction (PPID, formerly equine Cushing’s disease) particularly vulnerable.

“PPID generally compromises the abdominal muscle tone and, as they get heavier toward the end of pregnancy, they may have ruptured muscles or prepubic tendon rupture,” Tibary says.

Monitoring the Mare for Colic

Typical signs of colic include pawing, flank-watching, and rolling. But late-gestation mares can show broader signs, Dechant says. Watch for “changes in attitude (agitated or dull), changes in manure consistency (loose or dry), decreased or absent manure output, reduced or absent appetite, and lying down more often.”

Watch the udder “for premature signs of udder development or dripping of secretions. Vulvar discharge or development of abdominal edema or swelling are also important to monitor,” she adds.

Dechant further recommends owners learn to take their horse’s vital signs (temperature, heart rate, and respiratory rate). Late gestation mares often have mildly increased heart rates and respiratory rates. Sudden or moderate-to-severe increases in heart rate or respiratory rate are not normal, she says.

Call the veterinarian when you see obvious signs of discomfort; mild signs of discomfort that last more than one to two hours; or multiple simultaneous signs (such as mild discomfort in addition to not eating or abnormal vital signs).

Treatment Options for Late-Gestation Colic

The mare’s treatment depends on the diagnosis, of course. For late-gestation colics that get sent to the clinic, approximately half respond to medical treatment, while half require colic surgery, Dechant says.

“Some problems, such as uterine torsion, have different treatment options depending on the clinical signs, gestation length, and clinician preference,” Dechant notes. “Some problems, such as hydrops or body-wall tears, require confinement, analgesia, and abdominal support wraps.”

For other problems causing abdominal pain, the mare might need medication to fight infection or prevent pregnancy loss, Dechant says.

GI Colic Treatment

Mares with a large colon volvulus need to go straight to surgery; time is critical.

“The sooner they can get to a hospital, the sooner they can get anesthetized, the sooner that they can get on the table, the more likely they are to survive,” VanderBroek says. If it takes three or four hours to arrive at the hospital, “the likelihood that they’re going to survive decreases.”

For other kinds of GI colics, treatment might include administering non-steroidal anti-inflammatory drugs (NSAID) for pain; using a nasogastric tube to check for reflux; or administering fluids, Strachota says.

VanderBroek notes that pain plays a role in determining whether a case needs to go to surgery. Compromised blood supply is another factor. If something’s twisted or strangulating, “I recommend surgery because that’s going to be the only fix,” she says. “You cannot resolve a large colon volvulus or another strangulating lesion medically. There’s just no way to do that.”

Pregnancy-Related Colic Treatment

If your mare has uterine torsion, a veterinary team might attempt to roll the mare using the “plank on the flank” technique.

The veterinarian using this method first determines the direction of the twist—counterclockwise or clockwise. Next, after anesthetizing the mare, placing her on her side, and setting a wood plank on her belly in a specific area (TheHorse.com/124561), someone kneels on the plank, while other handlers roll the mare to her other side. The person kneeling holds the uterus still while the mare is rolled to correct the torsion.

The technique proves successful about 80% of the time, Tibary says. To attempt it veterinarians must know both how to perform the maneuver and the direction of the torsion.

“If you start rolling the mare every which way, and you don’t know the direction of the torsion, you could rupture the uterus,” Tibary says.

Veterinarians can also address torsions surgically.

“Mare survival is approximately 85-90% and up to 80% live birth rates if the mare is less than 320 days gestation, and the mare is not in shock or compromised,” Dechant says.

Prognosis After Treatment

Survival rates after colic surgery in late-gestation mares average 60-65%, slightly lower than rates in nonpregnant horses, Dechant says.

When the mare survives, “approximately 75% of these cases can have successful pregnancy outcomes” depending on the severity, she adds.

Mares with hydrops have an excellent survival rate, provided they do not have body wall tears or go into shock, Dechant says, though they typically lose the fetus. But in many of these cases, mares can be successfully rebred and deliver foals naturally.

Preventing Late-Gestation Colic

Preventing GI Colics

“Owners will say, ‘What can I do to ensure that my horse never colics?’ and my response is, ‘Don’t get a horse,’ ” VanderBroek says. “Because there’s no way to completely prevent colic.”

Still, our experts have some advice:

• Ensure horses have hay in front of them all the time so they eat throughout the day. “If the colon is full of fiber when it twists, it doesn’t compromise the blood supply quite as much,” VanderBroek says. “Horses were not meant to eat large grain meals twice daily.”
• Feed pregnant mares and lactating mares according to their body condition and their actual energy demands, says Strachota. This will ensure they receive balanced nutrition, which supports their gut health and reduces the risk of digestive disturbances.
• If you make changes in feed and management, do it gradually to help the sensitive bugs in the gut adjust.
• Hydration can prevent impactions. Try flavored electrolytes if your mare needs more water, Strachota says.

Preventing Pregnancy-Related Colics

Some pregnancy-related colics have unknown causes.

Uterine torsion is “bad luck,” VanderBroek says; there’s nothing you can do to prevent it.

Theories exist about the cause of hydrops but “we don’t really know,” Tibary says.

Strachota emphasizes the role of biosecurity in preventing abortion. Mares should be isolated from animals that have left the property and returned, and they should be kept away from high-traffic areas.

Tibary stresses the importance of checking a mare’s pregnancy early because twin pregnancies are “something that is either going to result in abortion or result in some pretty serious problems.”

If your veterinarian finds one embryo but the ovaries show more than one ovulation during the first pregnancy check, you might need to check again later, he says. Vets should examine the mare at five months of gestation to verify everything is normal. These checks can identify problems that could lead to abortion, such as a thickening or separation of the placenta.

Take-Home Message

Late in pregnancy, mares’ abdominal space is a limiting factor, and they can experience colic, whether due to gastrointestinal problems, uterine torsion, abortion, or dystocia.

“There are other possible causes for colic, but those three come to my mind first,” VanderBroek says. Deciphering a mare’s clinical signs can be tricky and time matters, so call the veterinarian sooner rather than later.

This article is from the Winter 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.

What to consider when contemplating sending your horse to colic surgery

You’ve been with your colicky mare for hours, hand-walking her and waiting to see if she’ll respond to medical therapy. When your veterinarian finally calls it and says you need to take her to the local referral center for a surgical consultation, your stomach drops. The barn closes in, and you suddenly feel like you’re in a nightmare version of the game “Would you rather.” Would you rather take your horse to surgery and risk major complications during or after? Or humanely euthanize so she is no longer in pain and won’t undergo a major operation?

“Surgical treatment comes with the risk of complications, which we define as any deviation from the ideal postoperative course,” says Marco Gandini, DVM, PhD, associate professor in the University of Turin’s Department of Veterinary Sciences, in Italy. “Complications are unexpected negative outcomes. These differ from procedural failures where the purpose of the procedure itself was not fulfilled and from surgical sequelae, which are adverse effects inherent to a given procedure.”

Such unexpected complications can develop despite exemplary pre-, intra-, and postoperative care. And in the case of colic surgery, even the most minor complications can spiral, with some severe ones leading to euthanasia. Complications might also cause in-hospital costs to skyrocket despite a technically successful surgery.

“That said, depending on the type of colic and surgical procedure, complication rates can be low and survival rates can be quite high,” says David E. Freeman, MVB, MRCVS, PhD, Dipl. ACVS, Appleton endowed professor in the University of Florida’s Department of Large Animal Clinical Sciences, in Gainesville.

How high can those survival rates reach?

Some published studies relay exact figures. Spadari et al. (2023), for instance, stated the short-term survival rate was 68.5% for all horses undergoing surgery and 80% for all horses surviving anesthesia.

Freeman hesitates to give his clients a flat percentage when discussing survival after colic surgery. “If we give an 80% survival rate, it’s okay if you’re in that 80%. But someone has to be in the 20%,” he says. “You have to present survival rates carefully, and I would never present just a rate alone but as part of a discussion.

“Something simple such as a displacement, intraluminal obstruction, or nonstrangulating disease generally has a pretty good prognosis, close to 95-98%,” he adds. “But for the strangulating diseases, it’s not as high. I emphasize that when we do the surgery, we will learn more about the prognosis. But my typical approach is to give the horse a chance within reason.”

So how do you decide if you’re going to take your horse to surgery?

Playing the Odds

Although colic is a major reason for emergency consultations with equine veterinarians, most cases can be managed medically. Only an estimated 8-20% of cases require hospitalization for intensive care. Many of those can still be successfully managed medically (Stratico et al., 2022; Dybkjaer et al., 2022).  Further, only 19-43% of horses hospitalized due to colic need surgical treatment (Dybkjaer et al., 2022).

These data are in line with those Freeman presents: “Approximately 1.4-17.5% of horses with colic require or undergo surgery.”

Motivators and Barriers for Surgical Consent

In a recently published study, Kate Averay, BSc, DVM, and her colleagues at the University of Sydney School of Veterinary Science, in Australia, reported results from a questionnaire horse owners in Australia and New Zealand completed about motivators and barriers for consenting to exploratory surgery in colicking horses. Of the 1,502 owners that completed surveys, 18.7% stated they would absolutely consent to surgery, and 26.1% relayed they would not.

“Thus, half of all survey respondents said they would consider exploratory abdominal surgery if their horse was colicking,” says Averay.

High chance of survival and the horse’s emotional value were top factors supporting an owner’s decision to choose surgery. Owners who originally said they would consider or consent to surgery said financial costs, uncertain probability of survival, and concern for the welfare of their horse would make them reconsider their answer, electing not to pursue surgery, says Averay.

“Additionally, owners who originally said they would not consent to surgery did state that they might reconsider if there was a high probability of survival and if the only alternative was humane euthanasia,” she explains. 

She also found that owners of insured horses were more likely to consider or consent to exploratory surgery. When owners anticipated survival rates below 50%, reduced athleticism, or a convalescent time of more than 12 months, they were less likely to consider surgery. Further, owners of older horses were less likely to elect surgery.

“The results of this survey highlight the importance of educating clients regarding colic surgery to help them to make informed decisions,” says Averay. “I recommend owners consider in advance whether they would take their horse to colic surgery if needed. If they have a horse in which colic surgery would be an option, it is important to have decided your equine referral hospital of choice, have transport to the hospital arranged, and have the necessary funds or deposit available. It may also be prudent to have investigated options for veterinary insurance coverage.”

What to Expect With the ­Unexpected

Gandini and colleague Gessica Giusto, DVM, PhD, reviewed colic surgery literature. They identified a wide range of reported postsurgical complications in colic patients. They then proposed a classification system for defining postoperative complications. It grades complications as Class 1 through 6 based on whether the condition resolved medically with the treatment of symptoms or if the complications were severe enough to require a second surgery or euthanasia. They applied the classification system (see the table below) to data from 190 horses that underwent colic surgery at their ­institution.

Gandini and Giusto reported that 47 of the 190 horses (24.7%) had no complications following colic surgery. 

“Our data also showed that the less severe complications occurred more frequently than severe complications,” Gandini says. “In fact, of those horses that had some complications (143), 116 (81.1%) were successfully managed medically. Seven (4.9%) required a second surgery, and 14 (9.8%) unfortunately required euthanasia.”

Thus, approximately 89% of horses either had no complications or complications successfully managed medically, he explains.

Horses might have more than one complication concurrently. Of the 190 horses in the study, 25.8% had one complication, 20% had two complications, 13.2% had three, 11.6% had four, and 4.7% had five.  

Specific Complications

Incisional Issues

Based on Gandini and his colleagues’ data, the most frequently reported complications are incisional issues. A minor surgical complication such as a mild incision infection could lead to more severe complications, such as a hernia or even complete dehiscence (reopening) and evisceration (protrusion of the intestines through the surgical site). In their study incisional drainage was a Class 2 complication, affecting 23.7% of the horses.

Postoperative Colic

“Two of the most common Class 3 complications we identified were postoperative colic (POC) and postoperative reflux (POR, where GI fluid accumulates and fills the stomach and must be removed by nasogastric intubation),” says Gandini. “These complications may have many causes, ranging from adaptation of the intestine to anastomosis (where a section of intestine was removed and the healthy parts reattached) to failure of the intestine to regain normal motility (movement of digesta through the GI tract).”

“We usually see these complications following small intestinal surgery, and they need aggressive and prompt management, potentially even a second surgery,” says Freeman.

One cause of postoperative colic is a segment of bowel that is twisted or strangulated or dies after the first surgery, he says.

“Lots of things can go wrong,” he adds. “When we’re faced with POC, we can administer intravenous fluids, remove fluid from the stomach, and provide analgesics for pain relief. But I don’t like to wait too long before taking these horses back to surgery.”

For owners concerned about a second surgery, Freeman says, “A second surgery might not fix everything. But what we do know is that for uncontrollable POC there is no choice. The only options are humane euthanasia or surgery.”

Postoperative Reflux

“For every surgeon performing small intestinal surgery, POR is a big concern,” says Freeman. “My typical approach to POR is managing these horses medically for 48 hours or so, and if they don’t respond to treatment in that time, we have a serious discussion for the need for a second surgery.”

Findings during a second surgery can include an impacted anastomosis site in the small intestine. “Sometimes we don’t find anything except the anastomosis is simply not working. If we redo the anastomosis, some horses do fine,” he says.

Freeman reports a “good survival rate” and elimination of reflux after a second surgery in most cases.

Laminitis

“Laminitis is a terrible complication, and the long-term prognosis is not good,” says Freeman. “It’s unfortunate because the gastrointestinal tract is often functioning very well in these patients.” Laminitis is a painful disease in which the tissues that suspend the coffin bone within the hoof capsule become damaged and inflamed. In severe cases they separate, releasing the coffin bone to rotate downward or sink.

Sepsis (bodywide inflammation) can play a role in the development of laminitis. However, horses with equine metabolic syndrome might have a higher risk of ­postoperative laminitis than nonmetabolic horses.

“And we can never predict the outcome,” he says. “We can say it’s a mild case. But then a week later they’re sinking and the coffin bone is coming through the sole.”

Dispelling Myths

“Owners are still embracing myths regarding colic that they need to shed immediately,” Freeman says.

One is that older horses can’t tolerate anesthesia and surgery or that the horse “isn’t the same” after surgery. “This is simply not true,” he says. “Colic surgery is not a death sentence, just an interruption in progress. Those horses can meet their full athletic potential.”

Freeman says owners can be overly pessimistic about proceeding with colic surgery on older horses. However, many studies have clearly demonstrated that senior horses (20-plus years old) can handle transportation, anesthesia, and surgery as well as younger horses, with similar survival and complication rates.

“Colic in older horses is most likely caused by a strangulating lipoma, which should be approached as a true emergency that prompts immediate referral to a surgical facility,” Freeman says.

Secret to Success: Early Referral

Freeman acknowledges that primary care veterinarians are very good at treating and managing colic on the farm with diagnostics, analgesics, and fluid therapy. Perhaps too good, he says.

“Treating the horse on the farm appeals to the owner a lot,” he explains. “But it’s expensive and delays surgery. This costs money that the owner won’t have for surgery if that is needed. It also adds an unnecessary and life-threatening delay.”

He says if the referring veterinarian suspects the case needs another opinion because of a lack of progress, owners must make that decision sooner.

“If the surgeon gets the horse early enough, then they might not need a resection and anastomosis,” Freeman says. “They might just need a simple correction. We showed that horses that came quickly enough, even with a strangulating disease, did much better than those that required resection and anastomosis (Rudnick MJ et al., 2022).

“I’ve said many times, if I had only got this horse 12 hours earlier, a favorable survival rate would have been much more likely,” he adds. “It may have been 95% then. But if there is a delay in referral, then by the time I see it the chances of success are down to 65-75%.”

Take-Home Message

There are no promises when it comes to colic surgery in horses. The good news is mild complications occur far more frequently than serious ones, if at all. What is the easiest way to reduce postoperative complications? “Get them to a surgical facility, and get the surgery done ASAP,” says Freeman.

Recurrent colic—the type of abdominal pain that goes away but just keeps coming back—isn’t technically considered a disease itself.

Rather, recurrent colic is the result of other underlying causes, such as inflammatory bowel disease (IBD), intestinal adhesions, gastric ulcers, and/or dental problems. In some cases the primary cause isn’t even a gastrointestinal issue at all—such as when ovarian cysts, displaced ligaments, or chronic stress trigger abdominal pain.

Determining the Cause of Recurrent Colic in Horses

That’s why the first step in managing recurrent colic should always be to take a step back and look at what pathologies might be behind it, says Alicia Long, DVM, Dipl. ACVIM (LA), ACVECC (LA), assistant professor in Large Animal Emergency and Critical Care at the University of Pennsylvania’s New Bolton Center, in Kennett Square. Some causal diseases, such as gastric ulcers, reproductive system disorders, enteroliths (intestinal stones or calculi), and enteropathies (disease or damage of the intestinal tract), can be successfully treated with medications, changes in management, and/or surgery.

The underlying issue might not even be a physical disease at all but, rather, inappropriate management, adds Kris Hiney, PhD, associate professor and extension specialist in Animal and Food Sciences at Oklahoma State University, in Stillwater. “Don’t forget that physiological health depends on mental health,” she says. “That’s super important.”

Finding the cause of your horse’s recurrent colic could take weeks, months, or even longer, says Long. When you get a diagnosis, there aren’t always rapid treatment options—which is the case with spasmodic gas colic and colon displacement—arguably two of the most common sources of recurrent colic, she says. Worse, in some cases, there might not be any diagnosis at all.

In the absence of a diagnosis or targeted treatment plan, it’s critical to feed the horse in a way that provides relief, our sources say. In addition, following a carefully devised plan could lead to valuable clues that help pinpoint the cause.

And although robust research is still needed, practical experience suggests a well-designed feeding regimen might even—in some cases—give the digestive system just the break it needs to heal and get back on track, Long says.

“It’s sort of like resetting the system,” she explains. “The hope is that it would be just an intermediate phase to then go back to more normal.”

Importantly, feeding the recurrent colic horse is never as simple as throwing in a dietary supplement, Hiney emphasizes. “I would really take a holistic look at the entire program for the horse before saying, ‘Oh, I’ll just give him a probiotic,’ ” she says. “Because that’s not going to help if the problem is somewhere else.”

To help you understand the best ways to feed your recurrent colic patient while awaiting a diagnosis or targeted treatment, we’ve provided these five helpful tips.

1. Go for Low-Bulk Fiber

Horses evolved to thrive on bulk fiber such as long-stem hay and grass, and even leaves and small branches. But the digestive system—particularly the small intestine—works hard to break down all that bulk, Long says. To give the intestines some rest, she recommends feeding low-bulk fiber such as chopped hay, hay cubes, and pellets.

Based on various clinical cases she’s seen, Long notes that low bulk seems particularly beneficial for horses with inflammatory intestinal conditions such as IBD. “Basically, you’re making it really easy for those intestinal cells to digest food,” she explains.

Made of finely ground fiber, pellets offer “the most extreme of low bulk,” says Long. She’s found pellets work best in confirmed IBD cases. Because hay pellets are hard, they need to be soaked for easier chewing. When the diagnosis is uncertain, horse owners can try chopped hay or cubes first, if they prefer.

Hiney says she looks out for any forage that might be “too coarse,” especially when the recurrent colic patient is an older horse with dental issues. “Does he need to be on a finer stem, or perhaps less-mature forage?” she asks.

Fresh grass usually makes a great low-bulk forage, provided horses can chew it, Long says. Horses with recurrent colic can benefit from full- or part-time pasture, as long as their dental and metabolic health—particularly concerning laminitis—allow it. This approach offers the added benefit of mimicking the natural behavior of horses, which evolved to have constant access to forage and move regularly to obtain it.

While researchers haven’t linked high-starch diets and recurrent colic, Long says she nonetheless recommends keeping concentrate feeds to a minimum for these horses. Any concentrates should be fed on a full stomach of forage to avoid digestive upset, she adds.

Horses with recurrent colic needing extra energy for performance or weight gain could consume fats and oils instead of concentrates, Long says. And all horses on forage-focused diets need a balancer to shore up their vitamin and mineral intake.

2. Limit Variety

Free-roaming feral horses consume dozens of plant species. But to allow an upset digestive system some rest, it’s important to keep your horse’s “salads” simple, our sources say.

“In general, limit the number of different ingredients you’re giving your horses—
especially those whose intestines aren’t totally normal from a functional standpoint,” Long says.

That includes the supplements we’re hoping could be helpful, as well as the treats we use for training or just to show our love. “Apples, carrots, and peppermints have simple ingredients versus processed treats,” she explains.

Providing pasture in addition to stored forage (hay and hay products) also constitutes variety, says Hiney. That creates somewhat of a conundrum because, again, horses—and notably those with recurrent colic—usually benefit from fresh grass. The trick is introducing the variety slowly, increasing the amount of turnout time over a matter of weeks.

3. Scrutinize Your Forage, Pasture, and Bedding

Do you really know what’s in your forage, out in your field, and under your horse’s feet? Examining the composition of these food sources could provide crucial insights into what triggers your horse’s colic episodes, Long and Hiney say.

Hiney recommends regularly checking your turnout areas for toxic plants such as branching ivy, sycamore maple (Acer pseudoplatanus), or buttercups.

Fence lines are likely spots for unintended plants, including weeds and poisonous species such as pokeweed, distributed by birds in their droppings. “Really look at everything that could be going on,” she says. “They could all be part of the problem.”

Grass length could also cause trouble if a horse has dental issues that prevent proper chewing. Long fibers are harder to digest.

You can work with an extension agent to evaluate your pastures and hay and help you identify any toxic plants.

Sand buildup in the digestive system can also create digestive issues, particularly sand colic. So, it’s important to know if you have sandy soils and if your horse’s recurrent colic might be associated with that.

Owners should thoroughly inspect their stored forage for dust, mold, coarse texture, or poor quality in general. Any of these issues could further upset a sensitive digestive system, our sources say. In addition, they need to watch for dead animals and other foreign objects that could cause disease or injury.

Finally, inspect your bedding for similar problems, and observe your horse’s behavior. Is he eating his bedding? Straw contains coarse, long fibers that are difficult to digest, but bored, hungry horses, or those needing to chew or lacking long fibers in their diet, are prone to eat it, Long says.

While shavings might be a better option, some horses—especially hungry ones—eat them as well. Long says researchers have not documented any cases of horses developing recurrent colic because they consumed shavings. Even so, it’s worth keeping an eye on what horses are doing with their bedding. “It sometimes requires some experimenting to keep them from eating it,” she says.

4. Prioritize Consistency

Generally speaking, horses are creatures of habit. Those with recurrent colic thus face fewer challenges when they have consistent management—meaning consistent meals at consistent times of day in consistent settings.

“Often what you see with these recurrent colic horses is that they colic with changes in routine—even changes in weather,” Long says. “Obviously, the weather’s going to do what the weather’s going to do. But if you can try to make sure that their feeding is as consistent as possible, that’s going to be a big thing, too.”

That routine means what time, how much, and what you’re feeding—right down to the same batches of hay from the same source, she says.

However, consistency goes far beyond just feeding (and weather), Hiney adds. Susceptible horses need welfare-friendly environments that meet all their unique natural needs, such as forage, companionship, and free movement.

“My answer is always to go through all of the management first, doing all the things that are logical for the horse,” she says. “People like to go first to supplements right away, but you really need to make sure your management program is where it needs to be before you start adding things on top.”

5. Try Supplements and Other Changes One at a Time

Once you’ve examined and addressed your horse’s diet and management, try adding or removing an element to see what helps—or what, unintentionally, might make things worse.

“It’s a little bit of trying and seeing,” Long explains.

Specifically, that means experimenting with different types of hay or pasture, feeding times, and even surroundings or nearby companions, notes Hiney.

“So, ask yourself, ‘Okay, I’m changing this, did this help?’ ” she says. “You need to really start figuring out what works and what doesn’t for each horse. Dialing into the needs of that individual horse is how we want to do it.”

Supplements such as antacids, pectins, lecithins, aloe vera, and papaya might be helpful and, in fact, some probably are, says Hiney. However, the current research is too limited to provide clear recommendations.

“If you’re going to do supplements, you’ve got to be very clinical in your approach,” she says. “So don’t just throw everything at them. Try one thing, then give it a good chance (at least a month) to see if it does anything before you switch.”

This deliberate approach can help you determine what’s responsible for improvements—management or dietary changes or the product.

Importantly, owners need to keep in mind that frequent changes could themselves trigger colic episodes in a colic-prone horse, she adds. Consult an equine nutritionist about dietary management and work with your veterinarian to create a comprehensive health plan for such a horse.

Take-Home Message

Recurrent colic threatens horses’ health and welfare and causes significant stress and frustration for owners. A few helpful feeding tips can give them a chance to take a break and possibly even recover. Scientists still need to gather significantly more data before making evidence-based recommendations. In the meantime our experts advise easing the recurrent colic horse’s digestive burden with consistent, simple, low-bulk forage diets and a welfare-friendly management approach, while making changes gradually.

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.

Sand accumulation in the gastrointestinal (GI) tract of horses occurs commonly in regions with sandy soils, including Arizona, California, Florida, New Mexico, and Texas. Affected horses consume the sand inadvertently while grazing or eating off the ground. Horses housed on drylots with sand or dirt as the footing are more predisposed to picking up and ingesting sand as they eat, particularly if they are fed off the ground. Other predisposing factors can include poor-quality feed, overgrazed or overstocked pastures, and hierarchy if horses are housed together. Because sand weighs more and is finer than feed, it tends to settle and accumulate in a layer on the bottom of the large colon. A significant amount of sand can build up in the gut over time, leading to obstructions and irritation of the GI tract lining and resulting signs of colic (abdominal pain), weight loss, and diarrhea.

Diagnosing Sand Colic

If a horse exhibits signs of colic, and the owner or veterinarian believes sand might be a contributing factor, certain diagnostics can help confirm their suspicions. In addition to the routine colic diagnostic work-up, careful auscultation (listening with a stethoscope) of the ventral (lower) abdomen might reveal oceanlike sounds indicating the presence of sand. Veterinarians can also measure fecal sedimentation by placing fecal balls in a rectal sleeve and adding water to see if sand accumulates in the fingers of the glove. However, these methods are not always accurate, and horses with significant sand accumulations might not have sand in their feces at the time of examination. An ultrasound exam can help identify the presence of sand, but it can be subjective and does not help the vet quantify how much sand is present.

Gastrointestinal tract radiographs allow veterinarians to definitively identify sand in the gut and quantify how much has accumulated. The downside is this diagnostic modality might only be available in a hospital setting and not in the field, particularly for larger horses. Abdominal radiography is the best diagnostic method for evaluating the amount of sand accumulation, and it can also serve as a tool for monitoring sand disappearance with treatment. Further, evaluating radiographs for excessive gas accumulation might increase the index of suspicion of a displacement or complete obstruction in painful horses and expedite going to surgery if colic signs persist despite medical treatment.

Treating Sand Colic

Medical treatment of sand impaction is similar to that of other colic types and includes rehydration by intravenous (IV) or enteral methods and giving laxatives. Enteral fluids are administered via nasogastric tube passed through the nasal passages to the esophagus and stomach. This allows administration of a large quantity of water (up to 7-8 liters in an average 1,100-pound horse) and electrolytes and supplies the GI tract directly. Laxatives, such as magnesium sulfate (Epsom salts) can also be administered to help break up possible impactions. Mineral oil is usually not as effective, as it tends to pass around the sand. Veterinarians usually administer psyllium to help evacuate the sand, but not until the horse is passing formed manure and any possible obstruction has resolved.

If colic signs continue to progress despite medical therapy, surgical intervention to remove the sand and resolve the obstruction or displacement might be necessary.

Prognosis for medical and surgical management of sand colic is good, and most horses respond well to treatment. The most severe complication associated with sand colic is rupture of a portion of the GI tract due to complete obstruction and damage to the bowel wall.

Preventing Sand Colic

The most important factors in preventing sand colic are management and reducing horses’ access to sand. If restricting sand access is not possible, then ensure horses are not fed on the ground. Tubs, haynets, and feeders can help reduce their potential for ingesting sand with food. Laying down rubber mats to catch dropped hay or grain can further reduce sand ingestion. Remember to clean the mats and tubs regularly, because sand-filled feeders and mats defeat the purpose of their use. Good-quality feed is also important. Feeding psyllium pellets one week a month can help keep sand passing through the GI tract rather than accumulating in it. However, this should be done in addition to and not in lieu of these management strategies.

Dealing With Equine Colic: Here Are 33 Do’s and Don’ts

Do you know what to do–and just as importantly, what not to do–if your horse displays vague, mild, or serious signs of what might be colic? Your answer could save your horse’s life.

Getting back to basics might be the key to keeping the largest portion of the horse’s GI tract functioning properly

Horses are powerful, athletic animals. Their digestive systems, however, are delicate compared to those of most other types of livestock. Ruminants such as cattle and sheep have multicompartment stomachs. Saliva created by chewing a cud processes food in the front half of ruminants’ digestive tracts. Horses, however, rely on a metabolically complex fermentation process. And because horses only have one stomach, most of that fermentation occurs in the back part or hindgut.

Despite making up the largest portion of a horse’s gastrointestinal (GI) tract, the hindgut, which includes the cecum and large colon (or large intestine), often receives far less attention from owners than the stomach or small intestine, says Kenneth Kopp, DVM, a consulting veterinarian based in St. Louis, Missouri.

“The hindgut is about 25 gallons in a 1,000-pound horse—that’s huge compared to the (2-4-gallon) stomach,” he says. “The stomach is only 10% of the GI tract, but there’s such a focus there.” Billions of microorganisms, including protozoa, fungi, and bacteria, live in the hindgut. Their job is to convert carbohydrates into fatty acids and provide the horse with energy. Feed or forage might spend as much as 48 hours in the hindgut compared to a few hours or less in the small intestine.

“Ideally, by the time material gets to the hindgut, water-soluble carbohydrates and easily digestible proteins are already broken down and absorbed,” says Amy Biddle, PhD, assistant professor of animal science in the University of Delaware’s Department of Animal and Food Sciences, in Newark. “The fibrous part of feed, structural carbohydrates, are passed right through the small intestine to the hindgut, where the bacteria are really good at breaking them down and converting them to energy sources that the horse can utilize.”

The hindgut also absorbs short-chain fatty acids, which Biddle estimates provide at least 46% of the horse’s energy stores. For that and other reasons it is critical to keep those microorganisms happy and functioning properly.

Although researchers, veterinarians, and nutritionists know how critical hindgut function is to overall health, they know much less about this part of the digestive system than others. Generally, they’re unable to examine the hindgut with imaging equipment, and clinicians don’t perform autopsies in horses as frequently as they do in food animals. Veterinarians can use ultrasound to see small portions of the hindgut through the abdominal wall, and they can reach the colon with a GI “smart pill” endoscopic camera, but visibility is still limited. For the most part, researchers look to studies in humans and other livestock species and existing equine digestive system research to help horse owners promote a healthy hindgut.

Maintaining the Status Quo

The hindgut is naturally more basic than other parts of the digestive system, says Biddle. Large grain meals and sudden diet changes can promote the growth of lactic acid producers that rapidly shift the pH level in the hindgut and can lead to lactic acidosis, a dangerous situation in which the acidity increase kills off the beneficial bacterial population.

“This is why it is important to change feeds so slowly, so the microbes in the hindgut can keep up,” says Biddle, and so abrupt changes do not stress the system. “Especially if you’re going to change to a diet higher in nonstructural carbohydrates (simple sugars and fructans, which are readily digested), it has to be introduced slowly.”

Getting back to basics and simplifying meals is the best approach for maintaining a healthy hindgut. Ideally, you want to feed your horse a diet that’s high in forage and low in grains, says Anthony Blikslager, DVM, PhD, Dipl. ACVS, head of the department of clinical sciences and equine surgery and gastroenterology professor at North Carolina State University’s College of Veterinary Medicine, in Raleigh.

Horses evolved on ever-changing marginal grasslands. They were browsers that adapted to be grazers that rely on continual forage intake.

Blikslager says fresh grass is the ­ultimate forage for horses, but investing in high-quality hay is the best place to start improving the equine hindgut. He believes you can correct approximately 80% of a horse’s condition simply by adjusting the forage in the diet.

“When we see horses not holding their weight or running out of steam, that’s when we look at their diet and see if any minerals or vitamins are missing, particularly in certain (regions),” he says.

The National Research Council guidelines for nutrient requirements in horses are a good resource for building a diet around forage, Biddle says. She also recommends software programs such as FeedXL’s nutrition calculator to help design or evaluate individual diets. Performance horses, working horses, and lactating mares, for instance, have higher energy needs and, therefore, require more energy-dense diets.

“It’s all about keeping the bacteria happy, and that starts with high-quality forage as the foundation,” she says.

When Things Go Wrong

Abdominal pain, known as colic, is the most obvious sign the hindgut isn’t working well. Even mild grumpiness, especially when you touch a horse’s belly, could be symptomatic of an upset hindgut. Often, a horse that is “not cooperating” on the ground or under saddle could be feeling not quite right.

In his practice, Kopp has observed affected horses that love to eat hay but don’t like grain or consume it slowly. He has also seen horses constantly shifting weight from one hind leg to the other.

“It’s not colic, but is there low-grade inflammation in that hindgut?” he says. “When we start seeing some of those things, maybe the horse needs forage supplements for better hindgut health.”

The next most common complication is called leaky gut. The entire intestinal tract is lined with a thin layer of cells that create a barrier against stomach acid. Kopp explains that the cells line up side by side and attach in a similar construction to Velcro. If their integrity is compromised, leaking can occur.

“When we get a leak into the bloodstream from the gut, offending pathogens (disease-causing organisms) can lead to inflammation anywhere in the body,” Kopp says. “What researchers are finding is that this leaking and inflammation cycle may make horses more prone to pneumonia and mastitis (mammary gland inflammation) and even opens the possibility of allergies and autoimmune disease.”

Laminitis (a hoof disease that causes the laminae—tissues suspending the coffin bone within the hoof—to become damaged and inflamed) can be another complication of poor hindgut health. The laminar structures in the horse’s hoof are so delicate that the blood vessels cannot tolerate sudden change. If a large amount of undigested starch (e.g., from grain overload) enters the hindgut, for instance, acidosis can cause the bacteria to die and release endotoxins. If endotoxins suddenly leak into the horse’s system, they can trigger laminitis, Blikslager says.

Kopp says the most common form of hindgut-related laminitis is pasture-associated laminitis in horses with equine metabolic syndrome or pituitary pars intermedia dysfunction (aka equine Cushing’s disease), with the primary mechanism being insulin toxicity of the laminae.

“Mild leaky gut has been linked to insulin resistance and metabolic syndrome in other species and could very well be part of the problem in equines,” Kopp says. “Chronic low-grade leaky gut could help explain insulin resistance and laminitis risk in horses.”

Because we don’t fully understand leaky gut’s whole-body impact on horses, Kopp looks to human and food animal research for answers. He cites work Adam Moeser, PhD, DVM, a professor at Michigan State University College of Veterinary Medicine, has done in piglets that closely parallels studies of children and the lasting impact of early weaning.

“Findings are showing that weaning stress early in life leads to lifelong GI issues,” Kopp says. “The kids that were followed were found to have irritable bowel syndrome and chronic gut issues later in life, and Adam is seeing that in the piglets. Once they start leaking early in life, they’re more reactive to stressful situations later in life.”

What About Pre- or Probiotics?

If hindgut health relies on a balanced natural microbiome—an ecosystem of microscopic organisms—won’t feeding pre- and probiotics keep it healthy and avoid colic, leaky gut, and laminitis? Theoretically, giving the horse a prebiotic feeds the hindgut microbiome by providing a food source for the bacteria strains that already live there.

“Prebiotics typically contain yeast and fiber that are easily fermentable by bacteria and promote growth,” Biddle says.

Probiotics contain favorable bacteria and yeasts that might effect a change or encourage colonization. The biggest problem is not knowing how many of the live organisms will make it into the colon and what their physiological impact will be.

“It’s generally thought that probiotics give the bacteria a jolt in a favorable direction but then come back to a normal state,” Blikslager says. “It takes a lot to make a difference and why we tend to feed (these products) daily. Plus, no one has fully answered how many (bacteria or yeast) make it to the colon and (cause a) permanent change.”

Supplemental butyric acid, a short-chain fatty acid, is a new equine nutrition tool that could be a hindgut health game changer. It’s been shown to increase colonocyte growth, which is thought to contribute to a healthier gut barrier.

Management Practices to Support the Hindgut

While we need more research to better understand the equine hindgut, our sources agree that some management practices can influence hindgut health. For instance, it’s important to introduce or change hay just as gradually as you would transition to a new grain type.

Spreading meals throughout the day is ideal. Generally, horses receive meals twice a day because it is convenient for their caretakers. However, consuming multiple meals, especially for senior horses, is healthier.

Kopp emphasizes the importance of providing consistent fermentable fiber that feeds the hindgut bacteria. He is an advocate of chopped forage and hay cubes or pellets and has seen horses respond well to fermentable fibers such as shredded molasses-free beet pulp and soybean hulls.

Biddle encourages owners to monitor their horses’ manure to get a sense of what is normal for each animal. Horses should have well-formed fecal balls that aren’t hard. If the manure is hard, the horse might not be consuming enough water. A gritty consistency indicates the presence of sand.

“If you can get more water in the horse, it can aid in gut motility and prevent an impaction,” she says. “Soaked feeds like beet pulp, alfalfa cubes, adding some water to their grain, and giving their hay a little douse could be helpful in increasing water intake.”

Movement can also help hindgut health, says Blikslager. While not all horse temperaments or facilities are conducive to round-the-clock pasture time, it’s important to give the horse some opportunity to move every day.

Take-Home Message

Each horse is an individual, and as caretakers it’s our responsibility to feed them as such. This can admittedly be challenging on large farms feeding multiple horses in large paddocks. However, backyard horse owners and managers of smaller barns or farms with stabling have an opportunity to customize each diet to optimize hindgut health.

Q: I have a broodmare who is due to foal later this spring. My friend’s mare had a severe case of colic late in her pregnancy, and she lost both the mare and the foal. What steps can I take to minimize my mare’s chances of colic before she foals?

A:  I am so sorry to hear about your friend’s loss. It is never easy to lose an animal, especially when both mare and foal are lost. Colic is broadly defined as “abdominal pain,” which in broodmares is usually further classified as coming from either the gastrointestinal tract or the reproductive tract.

Daily assessment of your horse is always important but will become more so as your broodmare enters late gestation. Monitor water intake and hydration status to ensure your mare is getting enough water. You might notice her drinking more than the average 1 gallon per 100 pounds of body weight per day because she must also nourish the fetus. Adequate water intake is also important to ensure feedstuffs will continue to move through the entire digestive tract. Make sure water is always available to the mare. This might require adding buckets beyond what you normally provide, and checking water troughs more frequently.

It is important to make sure she is eating a well-balanced diet of good-quality forages, and grains/concentrates as needed to maintain proper body condition. Her nutrient requirements will increase as the pregnancy progresses, as she will be “eating for two”. You might need to make changes to your mare’s diet to make sure she is getting all the nutrients she and the fetus need. As the fetus develops, the space in the abdomen for the digestive tract decreases. When this occurs, mares might have a decrease in appetite, and might need a more concentrated form of nutrients, such as a commercial feed designed for broodmares. Any changes should be made gradually and after consulting with a qualified equine nutritionist.

Colic is not uncommon in broodmares in late gestation, as the fetus begins to take up more and more space in the abdomen. This “crowding” of the small and large intestines can cause some dysfunction. More mild incidents are thought to be caused by movement of the fetus, and will likely resolve on their own. You should be concerned if your mare’s behavior toward eating or drinking changes, or if the signs of colic persist. Some changes might be subtle, which is why it is important to monitor her behavior and vital signs daily.

Be familiar with the signs of colic and share this information with anyone else who will be routinely around your mare. As you get closer to the due date, be aware that some signs of labor are the same as a colic episode, since both labor and foaling cause abdominal pain. I cannot stress enough: If your horse is colicking, contact your veterinarian quickly so he or she can assess her, and the fetus, and determine a plan of action.

Colic is an age-old, life-threatening condition in horses that can be managed successfully if treated quickly. Sometimes, referral to a hospital is the best choice for the horse, even if the condition’s cause or severity is unknown on the farm.  

What Is Colic?

Colic is not an actual disease but rather a set of behaviors caused by pain, said Philip Johnson, BVSc, MS, MRCVS, Dipl. ACVIM-Large Animal Internal Medicine, ECEIM, professor at the University of Missouri, in Columbia, during his presentation at the 2023 EquiSummit, a virtual equine nutrition conference, held Sept. 5-6.

“Mild signs can include loss of interest in food, lethargy, shifting weight around, looking at their flanks, pawing at the ground with the front feet, stretching out, or adopting a straining stance like they’re straining to urinate,” he explained.

When that pain worsens and becomes more extreme, horses might try to lie down when being ridden, get up and down repeatedly, and roll. They often want to keep moving (propulsive walking), or they might fall or collapse.

Contributors, Causes, and Types of Colic

Colic occurs commonly because of the nature of the gastrointestinal tract. “The large intestine is very complicated,” said Johnson.

The large colon has two key “pinch points”: the pelvic flexure and the transverse colon, he said. Each is a 180-degree turn in the large intestine where digesta can easily lodge. Additionally, both locations have a marked narrowing of the lumen (a decrease in the inner diameter) that can contribute to impactions.

Diagnosing and Treating Colic in the Field

After getting the call for a colicky horse, a veterinarian’s goal is to arrive quickly, ensure horse and human safety, provide the horse with pain relief, and perform a comprehensive exam.

Looking at the gastrointestinal tract specifically, veterinarians assess gut sounds, note whether the horse is passing manure, determine if there is fluid accumulation in the stomach (there shouldn’t be), and potentially perform a rectal palpation, abdominal ultrasound, and abdominocentesis.

The rectal exam, said Johnson, is helpful, but a veterinarian can only feel so much of the abdominal cavity. Abdominocentesis involves collecting a sample of peritoneal fluid that bathes the abdominal organs.

“Just by looking at that fluid we can tell a lot. If the normally clear fluid is cloudy or orange/pink, there is cause for concern,” said Johnson. “Worse, if the fluid looks like fecal material, it suggests there was a rupture of the gastrointestinal tract.”

Veterinarians are increasingly using abdominal ultrasound, which can provide valuable information, such as a visual of loops of dilated small intestine that are cause for great concern.

“It’s also important to assess the horse’s cardiovascular system, including the heart rate, packed cell volume as a measure of hydration level, blood lactate levels, the color of the gums and lips, and pulse strength,” Johnson added.

Treatment at the farm includes pain relief and keeping the horse off food during the early hours following a colic episode.

For impactions, which are the most common type of colic, veterinarians administer fluids via nasogastric tube into the stomach. Those fluids, which can include mineral oil or other lubricants, are designed to dismantle the obstruction and stimulate the gastro-colic reflex.

“If the horse has a gas (spasmodic) colic or pelvic flexure impaction, they tend to do very well (with treatment),” relayed Johnson. However, a small portion of horses does not respond as positively to conventional therapies.

Red Flags

“If fluid is accumulating in the stomach and it is not improving over the course of two hours, (I always refer them),” said Johnson. “This indicates there is a severe problem, likely a small intestinal obstruction.”

In addition to fluid accumulation in the stomach, other red flags include severe small intestinal distention palpated on rectal exam, a patient that is refractory to pain medications, and a deterioration in cardiovascular status.

If the horse has a fever, it suggests the presence of colitis, enteritis, or peritonitis. If the horse has head trauma, it speaks to the severity of underlying colic (because they have clearly been rolling and thrashing).

Even if the horse ultimately ends up having a “negative referral,” meaning surgery was not needed, referring provides that patient with access to critical care, surgery if needed, round-the-clock observation, and a laboratory for quick results.

“They’ll need intravenous fluids at the very least, and that is easier to do in a referral setting,” Johnson advised. “Even if it ends up being a false alarm, it’s better to transport the patient to a facility that is equipped to manage severe colic sooner rather than later.”

Dr. Clair Thunes offers advice for preventing colic when the weather turns cold.12/5/2022 19:30

Listening to your horse’s gut sounds is part of a normal physical exam or vital signs check. Gut sounds should be present in all healthy horses, with approximately one to three gut sounds per minute indicating good digestive health. Listening to gut sounds when you suspect your horse is colicking might help you and your veterinarian determine the severity and cause of the colic.

Related Content:

• Dealing With Equine Colic: 33 Do’s and Don’ts
• Normal Adult Horse Vital Signs
• What You Should Know About Colic in Horses

How Does the Equine GI Tract Work?

Having a clear understanding of equine gastrointestinal (GI) tract structure and function maximizes an owner’s ability to recognize the wide array of digestive conditions that can threaten horse health. Anyone who has suffered through the roller coaster of colic or battled gastric ulcers in their horse knows the balance between GI clockwork and ticking time bomb is tenuous. Here’s a color-coded guide to how each region works to help your horse digest food and utilize the energy (calories) he needs to thrive.

What Could Go Wrong?

The intestinal tract’s massive length, volume, and continual change in diameter and direction put it at risk of several health conditions, including:

• Gastric ulcers Caused by splashing hydrochloric acid in the stomach’s squamous and glandular regions.
• Colic Abdominal pain due to intestinal twists, blockages (e.g., impactions), or even inflammation.
• Internal parasites Horses are most commonly affected by ascarid, small strongyle, and tapeworm infections.
• Diarrhea Causes include bacterial infections such as salmonella, diet changes, or stress.
• Hindgut acidosis A sudden decrease in pH can make the large intestine’s contents more acidic than normal, potentially causing ulceration and diarrhea.

Take-Home Message

Assess horses’ health daily, maintain a consistent forage-based diet, integrate feed changes slowly to allow the microorganisms in the GI tract to adapt to those alterations, and consult a veterinarian immediately if you discover any abnormalities.

Horses with sand accumulation are at risk of colic, discomfort, and fever. It’s easy to check for sand content in manure with this simple method that involves a fecal sample, plastic bag, and water. Christine Johnson, DVM, of Leclair Equine in Berthoud, Colorado, demonstrates how to do it.

Is she foaling or colicking? This question comes up frequently with late-term broodmares because both events are very painful and both manifest as signs of abdominal pain.

David Freeman, MVB, PhD, Dipl. ACVS, Appleton Endowed Professor at the University of Florida College of Veterinary Medicine, in Gainesville, sought to provide clarity during his presentation at the 2021 British Equine Veterinary Association Congress, held Sept. 4-7 virtually and in Birmingham.

Peripartum (before giving birth) abdominal pain has three possible causes, he said:

1. Normal parturition, where foaling is completed at the expected rate, and after delivery, the mare is more comfortable.
2. Dystocia (difficult birth) with prolonged or variable stages one and two of parturition (foaling).
3. Colic, which can have various effects on the delivery process and requires specific diagnostic tests to determine the cause.

Knowing What’s Normal

Because foaling is an inherently painful process, owners and veterinarians must understand the steps and signs of normal parturition before they can determine if the mare’s experiencing colic.

Freeman explained that the first stage of pregnancy typically includes active uterine contractions and dilation of the cervix. It should last 30 minutes to four hours, with the mare displaying very few signs of discomfort.

The second stage is far more dramatic, he said, characterized by the foal’s entrance into the birth canal, rupture of the allantoic sac, abdominal contractions, and delivery of the foal. This stage normally lasts five to 40 minutes.

Just before parturition starts, a normal foal lies so its dorsal aspect (back) is toward the ventrum of the mare. The front and hind feet and neck are flexed. During delivery, the foal’s hind limbs extend in dramatic form when the stifle encounters the brim of the pelvis and the reciprocal apparatus forces all the joints to go into rapid extension, Freeman explained.

“If the feet engage the uterine horn at this point, they can lacerate the uterus and create a uterine tear,” he said. “They can also hook a viscus in the abdomen and tear its attachments, which can cause catastrophic injury.”

Causes of Colic in Broodmares

“Any colic of gastrointestinal origin can develop at or during parturition, either as a coincidence or as a consequence of parturition,” said Freeman. “Some colics of gastrointestinal or urogenital origin are specific to parturition—they can precede or coincide with parturition, or they can be related to parturition. The important signs are those that persist after parturition. This is critical for your diagnostic steps.”

He said the types of intestinal disease that can occur in the peripartum period (shortly before, during, and immediately after giving birth) are essentially the same as you’d encounter in any horse at any time, including colitis, small intestine obstruction or strangulation, impaction, gas distention, and more. Serious conditions to be particularly aware of in late-term mares include:

• Large colon volvulus Freeman said this well-recognized cause of colic is responsible for 17-21% of all colic surgeries. Veterinarians see it most commonly in postpartum broodmares, but it can also develop during parturition.
• Tears The extension of the foal’s hind limb as it moves into position for delivery can cause structures and tissues such as the uterus, broad ligament, and jejunal mesentery to tear.
• Avulsion of the small colon from the mesocolon Freeman explained that this occurs when the foal’s foot engages the edge of the small colon and tears it off the mesenteric attachments.
• Cecal rupture or tear This can be mistaken for dystocia. Affected mares go into rapid endotoxemic shock and require assisted delivery. They must be euthanized, he said.
• Diaphragmatic hernia A previous or current parturition can cause a hernia. While small ones might be reparable, Freeman said large defects can require euthanasia of the mare.
• Urinary tract injuries If a urogenital tract laceration is large enough, other abdominal organs (e.g., intestines, bladder) can prolapse through it. These mares can develop tears in the urethra and bladder itself, said Freeman.
• Uterine torsion This condition causes low-grade colic similar to impaction colic. While it most commonly occurs in late gestation, on rare occasions it can develop shortly before parturition.

Should You Do a Cesarian Section?

This question arises frequently when managing mares with gastrointestinal or reproductive tract causes of colic that have not yet delivered the foal, said Freeman. However, “rarely, if ever, is a C section needed during colic surgery,” he said. “It’s usually done for the wrong reasons, such as to improve access or recovery. There are so many other ways to ensure a good outcome that it’s not necessary to do a C section.”

He warns a C section is likely to increase mare and foal mortality, partly because you might deliver a premature foal. Further, Freeman said, it adds a surgery and its associated risks, often to a horse that’s already undergoing major colic surgery.