Gastric Ulcers in Horses: Symptoms, Treatment, and Prevention

Gastric ulcers in horses are sores or erosions in the lining of the stomach. Your vet may call this equine gastric ulcer syndrome (EGUS). EGUS is an umbrella term that includes equine squamous gastric disease (ESGD), which affects the upper non-glandular part of the stomach, and equine glandular gastric disease (EGGD), which affects the lower glandular portion. These two forms can happen together, but they do not always behave the same way.

Horses are especially prone to stomach irritation because they produce stomach acid continuously, even when they are not eating. In a natural grazing lifestyle, forage and saliva help buffer that acid. When horses go long periods without forage, eat larger grain meals, travel often, train hard, or spend more time stalled, the stomach lining can become more vulnerable.

Ulcers are common in performance horses, but they are not limited to racehorses. Pleasure horses, foals, and horses under medical or social stress can also develop them. Some horses show obvious discomfort, while others only seem less willing to work, less interested in feed, or harder to saddle.

The good news is that many horses improve with a thoughtful plan. That plan usually combines medication, feeding changes, and management adjustments tailored to the horse's workload, housing, and risk factors.

Ulcers develop when the stomach's protective defenses are overwhelmed by acid, bile exposure, inflammation, or reduced blood flow to the lining. In horses, risk rises when normal grazing patterns are disrupted. Long gaps without forage, high-concentrate grain meals, intense exercise, stall confinement, travel, and social stress all increase the chance of EGUS.

The type of ulcer matters. Squamous ulcers are strongly linked to acid splash and prolonged acid exposure, especially in horses that train hard or spend time with an emptier stomach. Glandular ulcers appear to be more complex. They may involve impaired mucosal defense, stress, and inflammation, and they do not always respond as predictably to acid suppression alone.

Illness can also play a role. Horses dealing with other medical problems, reduced appetite, hospitalization, or pain are at higher risk. Prolonged or inappropriate use of some nonsteroidal anti-inflammatory drugs, such as phenylbutazone, can contribute to ulcer formation or worsen existing irritation.

Ulcers are common in racehorses and other performance horses, but they are not caused by one single mistake. Most cases reflect a mix of feeding pattern, workload, environment, and individual susceptibility. That is why prevention and treatment usually work best when medication is paired with practical management changes.

The most reliable way to diagnose gastric ulcers is gastroscopy, also called gastric endoscopy. Your vet passes a long endoscope into the stomach after a fasting period so the stomach lining can be examined directly. This allows your vet to confirm whether ulcers are present, estimate severity, and see whether the lesions are in the squamous region, glandular region, or both.

That location matters because treatment response can differ. Squamous disease often responds well to omeprazole-based therapy and management changes. Glandular disease may need a different or more layered plan, sometimes including additional medications and a closer look at stress, training, and feeding routine.

Your vet may also recommend other tests if the signs are not classic or if your horse has broader health concerns. Depending on the case, that can include a physical exam, body condition assessment, dental evaluation, fecal testing, bloodwork, or workup for colic, poor performance, or weight loss.

A treatment trial without scoping is sometimes used in real-world practice when cost or access is a concern, but it has limits. Improvement on medication does not prove ulcers were the only problem, and lack of improvement does not rule them out. If signs persist, recur, or are severe, gastroscopy gives the clearest answers.

Prevention focuses on supporting the horse's normal stomach physiology. Horses do best when they have regular access to forage, fewer long fasting periods, and less reliance on large grain meals. More turnout, more grazing time, and feeding hay before exercise can help reduce acid exposure in the upper stomach.

Management matters as much as medication. Travel, stall confinement, intense training, social disruption, and abrupt routine changes can all raise ulcer risk. If your horse is entering a stressful period, talk with your vet early about practical steps such as adjusting feed timing, increasing forage availability, reducing unnecessary stressors, and deciding whether preventive medication is appropriate.

For horses with a history of ulcers, recurrence prevention is often a long-term conversation. Some horses need changes in workload, feeding strategy, or housing to stay comfortable. Others may need short-term preventive plans around showing, hauling, or hospitalization. Your vet can help match the plan to your horse's risk level and your goals.

Do not assume every supplement marketed for ulcers is proven. Ask your vet which products have meaningful evidence, which medications are actually approved for prevention or treatment, and how to use them safely. A thoughtful prevention plan is usually more effective than reacting after signs return.