Gastric Ulcers

Gastric ulcers in horses are more common than most owners realize, and they're often sitting under our noses without us knowing because the signs aren't always obvious. These are erosions in the lining of the stomach, raw spots that develop when acid eats through the protective mucous layer, and they can range from small pinprick lesions to significant ulcers that bleed. What makes ulcers tricky is that some horses show dramatic symptoms while others with equally bad ulcers give almost nothing away except for subtle behavioral changes or performance decline.

Any horse can get gastric ulcers, but certain situations make them way more likely. Horses in heavy training, especially those raced or competed regularly, develop them at startling rates. Stabled horses fed grain-heavy diets are at higher risk than those on pasture. Even temperament matters—anxious, stressed horses prone to pacing or weaving tend toward ulcers because that stress messes with acid production and stomach function. Young horses and older horses both show susceptibility, and certain breeds like Thoroughbreds seem to deal with them more frequently than others.

The severity of gastric ulcers ranges from mild to serious, and this is important because a small ulcer might resolve with management changes alone while a severe one can cause real problems. Horses with bleeding ulcers can develop anemia. Chronic untreated ulcers can impact nutrient absorption, leaving your horse looking poor despite good feeding. In the worst cases, a perforated ulcer—one that eats all the way through the stomach wall—becomes a veterinary emergency. But here's the good news: caught early and managed right, most horses recover well.

Ulcers affect quality of life and performance differently depending on the horse and the severity. Some horses become grouchy, others lose condition, some develop quirky behaviors like crib-biting or excessive water drinking. Performance horses might suddenly seem lazy, resist the bit, or lack their usual spark. Even a horse that seems fine might have significant ulceration affecting his gut health and nutrient absorption at a cellular level. Understanding gastric ulcers matters because they're preventable and treatable, but only if you know what you're dealing with.

This guide walks you through what causes gastric ulcers, how to spot them before they become serious problems, what your vet will do to diagnose and treat them, and most importantly, how to manage your horse's life and feeding to prevent them from coming back once they're healed. You'll understand why certain management changes matter more than others and how to work with medication effectively rather than just dosing your horse and hoping for the best.

Gastric ulcers develop because of an imbalance between acid production and stomach protection. Horses produce acid constantly—their stomachs are designed to work that way because they evolved grazing all day on forage. But when we change how horses live and eat, that acid becomes a problem. The stomach's protective lining includes a mucous layer and bicarbonate secretion that normally keeps the acid from damaging tissue. Ulcers form when something disrupts this protection or when acid production increases beyond what the stomach can handle.

Stress is one of the biggest culprits, and this includes both physical and emotional stress. A horse shipped to a new location, entered in competition, or suddenly moved to a different training schedule experiences stress that increases acid production while simultaneously suppressing the stomach's protective mechanisms. Intensive training, especially when combined with diet changes and time away from home, creates a perfect storm for ulcer development. The link between stress and ulcers is so strong that high-level athletes seem almost guaranteed to deal with them unless actively managed.

Feeding practices directly cause gastric ulcers, and this is something you can actually control. Horses fed large grain meals and minimal hay are at much higher risk than those on forage-based diets. Grain ferments in the stomach and produces acid; hay, especially alfalfa, has natural buffering capacity. When you feed a horse primarily grain with grain-based supplements, you're essentially bathing that stomach lining in acid all day. Stabled horses eating hay from the ground less frequently than pastured horses graze are working with periods of high acidity and reduced buffering. Long periods without feed—such as overnight stabling without late-night hay—allow stomach acid to work unopposed on the mucous lining.

Medications matter too. Non-steroidal anti-inflammatory drugs like phenylbutazone (Bute), firocoxib (Equioxx), and others increase ulcer risk, especially with prolonged use. These drugs suppress protective mechanisms in the stomach lining while potentially increasing acid. A horse on pain management for lameness or arthritis might develop ulcers as a side effect of the medication meant to help him feel better. This is important information when working with your vet on treatment plans.

Age and genetics play roles that you can't change but should understand. Young horses, especially youngsters in early training, develop ulcers frequently. Older horses sometimes develop them too. Certain bloodlines and breeds show higher predisposition, with Thoroughbreds showing higher rates than some other breeds. Some horses seem naturally prone to ulcers no matter what you do, while others rarely develop them even under stressful conditions. This suggests genetic factors affecting acid production or stomach protection.

Other risk factors include changes in routine—moving to a new barn, changing trainers, altering feeding schedules, or modifying hay sources can all trigger ulcer development. Horses with underlying conditions affecting nutrient absorption or gut health are more vulnerable. Even excessive water intake can dilute stomach acid's protective effects in some situations. The combination of multiple risk factors creates much higher likelihood than any single factor alone.

The tricky part about gastric ulcers is that horses don't always show obvious signs, and when they do, the signs can look like other problems. Some owners don't realize their horse has ulcers until a vet diagnoses them during an exam for something else. That said, certain patterns should make you suspicious.

Early warning signs often include subtle behavioral changes that owners initially dismiss as personality or training issues. A horse might become grumpy about grooming, especially along the belly. He might be reluctant to go forward under saddle or lack his usual enthusiasm. Some horses develop a negative attitude about being worked, resisting transitions or seeming sour. Others become spookier or more reactive to stimuli that previously didn't bother them. These behavioral shifts happen because ulcers cause discomfort, and a horse in chronic pain gets cranky just like anyone else would.

Physical symptoms show up in ways owners sometimes miss. Poor body condition despite good feeding is a classic sign—the horse might look like he's not retaining nutrition properly, with a dull coat and loose flesh. Some horses develop a sunken appearance along the belly and flank. Others have indigestion-like signs: loose manure or intermittent diarrhea, lots of grain in the manure suggesting incomplete digestion, or a generally unhealthy stool. A few horses drink excessively and urinate frequently, changes in gut function related to stomach irritation.

Performance decline is often what brings ulcers to light. A horse that used to move forward enthusiastically becomes sluggish. A jumper loses interest in his job. A distance horse that had good stamina seems to fatigue quickly. Trainers often blame laziness or lack of conditioning, but when the vet finally looks at the stomach with a camera, there's the explanation. Some horses develop girthiness or sensitivity to abdominal pressure, actually wincing when you tighten the saddle or ride forward into collection.

Movement and posture can reflect stomach discomfort. Some horses stand with a stretched appearance, front legs extended forward and weight shifted back like they're trying to stretch their abdominal muscles. Others are restless, pawing, shifting weight, or spending excessive time lying down. Sweating without exertion sometimes indicates stomach discomfort rather than fear or exercise. A few horses develop cribbing or wind-sucking behaviors, repetitive behaviors sometimes associated with ulcer discomfort though the relationship isn't fully understood.

Symptoms typically develop gradually, not overnight. You might notice over weeks or months that something's off—a slight decline in performance, a behavioral change, a subtle shift in how the horse looks. Occasionally, especially if an ulcer bleeds, symptoms are acute: a horse might colic, produce dark tarry manure indicating intestinal bleeding, or suddenly become lethargic.

Emergency signs require immediate veterinary attention. Severe colic combined with a history of gastric issues suggests a bleeding ulcer or perforation. Dark tarry manure (melena), pale mucous membranes, rapid heart rate, and lethargy indicate significant blood loss. Continual straining or persistent colic unresponsive to initial treatment could mean a perforated ulcer. If your horse shows severe colic, call the vet immediately rather than waiting to see if he resolves on his own.

Your vet will start with history and physical examination. They'll ask detailed questions about feeding, training schedule, recent changes, behavioral shifts, and performance issues. They'll listen to your horse's gut sounds, palpate his abdomen, check his overall condition and attitude. The physical exam gives clues but isn't definitive—some horses with significant ulcers feel fine on examination.

The gold standard for diagnosis is gastroscopy, which means your vet passes a long camera through the horse's nostril into the stomach to directly visualize the stomach lining. This lets them see if ulcers are present, how many there are, how severe they are, and where they're located. The information from gastroscopy guides treatment decisions more than anything else because you can actually see what you're dealing with. Some vets use blood work to screen for ulcers—elevated gastrin levels or other markers suggest ulceration—but this isn't as specific as camera examination.

Treatment starts with medication. Omeprazole, a proton pump inhibitor, is the standard treatment. It reduces stomach acid production, giving ulcers a chance to heal. Treatment typically lasts four to twelve weeks depending on ulcer severity and how your horse responds. Your vet might add sucralfate, a paste that coats the stomach lining and provides protection. Some vets add H2 blockers like ranitidine, though omeprazole is usually sufficient. The medication itself is straightforward—paste or powder daily—but it's expensive, and long-term treatment gets costly.

Management changes happen alongside medication and matter enormously. You need to address the underlying causes that created the ulcers in the first place, or they'll come back the moment you stop the expensive medication. This means evaluating feeding, stress, activity, and other management factors that contributed to ulcer development.

Feed management is critical. Switch to a forage-based diet with the horse eating hay nearly constantly rather than large grain meals. Alfalfa hay is particularly helpful because it buffers stomach acid. If your horse needs grain for conditioning or performance, feed small frequent meals rather than large portions. Grain-based supplements should be minimal. Adequate pasture access is ideal—horses grazing naturally produce less acid. If your horse is stabled, provide hay available constantly, either from hay nets that slow consumption or from free access in the stall.

Stress reduction matters. If possible, reduce intense training temporarily while ulcers heal. Allow more turnout and social interaction. Minimize schedule changes and travel if feasible. Some horses benefit from calming supplements or medication during the healing period, though the medication part should be discussed with your vet. The goal is creating a lower-stress environment while the stomach heals.

If your horse is on NSAIDs for another condition, discuss alternatives with your vet. Sometimes you can use non-NSAID pain management like joint injections, chiropractic, or physical therapy instead. If NSAIDs are necessary, using them at the lowest effective dose for the shortest duration possible helps minimize ulcer risk. Some vets recommend additional protective medication alongside NSAIDs if they must be used.

Rechecking ulcers after treatment involves repeat gastroscopy, which costs money but shows whether healing is occurring and guides whether to continue medication or modify treatment. Most horses heal well with appropriate treatment, and ulcers don't leave permanent damage when resolved early. However, the recurrence rate is surprisingly high if you go back to the same management that caused them initially.

During the healing phase while your horse is on medication, the primary goal is creating optimal conditions for recovery. Stall rest isn't necessary unless recommended by your vet for another reason, and actually, gentle turnout helps. Grazing naturally buffers stomach acid and reduces stress, so letting your horse out even for a few hours daily is beneficial. If possible, provide pasture access for at least part of the day.

Feeding becomes the centerpiece of management. Forage should be available as much as possible, ideally hay twenty-four hours daily. Some barns have hay nets that slow consumption and spread hay throughout the day. If grazing, length of pasture access matters—more is better. Grain should be minimal or absent during the healing period. If you must feed grain, make it small meals (under two pounds) multiple times daily rather than one large meal. High-quality alfalfa hay is particularly beneficial because of its natural buffering capacity.

Water management is straightforward: keep fresh water available constantly. Some horses with ulcers benefit from slightly warmed water, which can be easier to digest. There's nothing wrong with mineral-rich water or adding electrolytes occasionally, but make sure the horse drinks adequate amounts. Dehydration stresses the system and slows healing.

Supplement wisely. Probiotics make sense because ulcers sometimes disrupt the healthy gut bacteria balance. Prebiotics that feed beneficial bacteria are helpful. Joint supplements without NSAIDs can support horses dealing with arthritis or lameness if that's contributing to stress. Calming supplements containing magnesium or herbal ingredients might help anxious horses. Avoid supplements high in inflammatory ingredients; check labels because many "joint" supplements include omega-6 fatty acids that can increase inflammation if not balanced with omega-3s.

Work and activity adjustment depends on your horse's condition and your vet's recommendations. Complete stall rest isn't necessary and might increase stress. Instead, reduce intensity and duration of work. A horse healing from ulcers doesn't need hard training, but gentle exercise seems beneficial. Even hand-walking helps psychologically and physically. Gradually increase activity as healing progresses.

Monitoring is important during healing. Note your horse's appetite, energy level, attitude, and manure consistency. A horse healing well gradually shows improved attitude, better appetite, and normal manure. Poor healing shows continued weight loss, persistent diarrhea, or lack of behavioral improvement. If your horse isn't improving after three to four weeks of treatment, contact your vet about potential medication adjustment or gastroscopy rechecking.

Once healed, the challenge becomes preventing recurrence. Some horses reheal quickly from gastric ulcers when the original cause is removed. Others seem prone to them long-term. For those prone horses, long-term low-dose omeprazole (twice weekly or similar schedule) sometimes prevents recurrence, though the cost and long-term implications should be discussed with your vet. The real solution is maintaining the management that heals them: forage-based feeding, stress reduction, and appropriate medication for any underlying conditions that contributed to the original ulcer development.

Prevention centers on the factors you actually control: feeding, stress, training intensity, and management consistency. The single most powerful prevention tool is feeding forage-based diets with horses eating nearly constantly. Horses on pasture for most of the day and hay available at night rarely develop ulcers unless they experience significant stress or medication use. This is nature's way of preventing the problem. When you must stable a horse, ensuring hay is available constantly is the next best thing.

Grain and concentrated feed should be minimal. If your horse needs conditioning, add calories through better-quality hay, added fats like oil or stabilized rice bran, and multiple small meals if necessary. Performance horses in heavy training sometimes require supplemental feeding, but it should be done carefully with small frequent meals rather than large portions. Even half the grain fed twice daily instead of once is significantly better for stomach health.

Reduce stress where possible. Consistent routines help. Adequate turnout and social interaction matter. Minimize unnecessary travel and training changes. For horses prone to anxiety, addressing the anxiety through management, training, or calming supplements before it develops into ulcers is smart prevention. Some horses benefit from calming supplements even during normal training.

If your horse requires NSAIDs for chronic pain, discuss prevention strategies with your vet. Potentially using gastroprotective medication alongside NSAIDs prevents ulcer development in horses that need pain management. This is especially true for older horses on chronic pain medication for arthritis or navicular disease.

Monitoring early signs prevents severe ulcers from developing. If you notice behavioral changes, performance decline, or early warning signs like girthiness or weight loss, have your vet evaluate the stomach before it becomes a major problem. Early diagnosis often means shorter treatment and easier recovery.

Prognosis for gastric ulcers is quite good. Most horses heal completely with appropriate treatment and management changes. There's no permanent scarring if ulcers heal properly, and the stomach returns to normal function. The limiting factor is owner compliance with management changes—horses that return to the feeding and management that caused the original ulcers often redevelop them, sometimes repeatedly. However, horses kept on appropriate forage-based diets with controlled stress and proper medication management maintain health long-term.

Recurrence is possible, sometimes likely in predisposed horses or those returning to problematic management. But even horses prone to ulcers stay healthy when managed properly. The key is understanding that ulcers aren't a one-time issue to medicate away and forget about—they're a signal that something about how you're managing your horse isn't working with his physiology. Fix that, and the ulcers resolve and don't come back. Keep doing the same thing, and they will.