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Also Known As

Equine gastric ulcers, Equine gastric ulcer syndrome, Gastric ulcers, Duodenal ulcers/p>


As in humans, ulcers in horses are festering sores that affect the stomach and the duodenum. Superficial ulcers are patches of inflamed and eroded mucosa covered by pus. Deeper ulcers affect the layers of the stomach wall and can range from small, one-inch ulcers to ulcers that are several inches in diameter.

With the advent of fiber optic gastroscopy, many veterinarians and horse owners have been surprised to find that the incidence of ulcers in horses is more common than once thought. Studies reveal that up to one-third of horses confined in stalls have ulcers and up to 60% of show horses and 90% of race horses develop moderate to severe ulcers.

Because ulcers are so common and can occur as a result of a number of factors, the condition is often referred to as "equine gastric ulcer syndrome" (EGUS) or "equine gastric ulcer disease" (EGUD).


  • Poor appetite
  • Weight loss and poor body condition
  • Mild colic
  • Poor performance
  • Poor hair coat
  • Attitude changes or mental dullness
  • Lying down more than normal


Multiple factors can increase the risk of ulcers in horses. Horses evolved as grazing animals, eating many small meals throughout the day. The stomach was rarely empty and because of the forage the horse was eating, stomach acid had less of a damaging effect. When a horse does not eat frequently, the acid builds up and ulcers may develop.

The type of feed, and, especially, the amount of roughage in the feed plays a role in ulcer development. Roughage requires chewing, and as the horse chews, the production of saliva is stimulated. The swallowed saliva helps neutralize stomach acid. The type of roughage is also important. Alfalfa is higher in calcium and it is thought that this may help decrease the risk of ulcers.

When concentrates and grains are fed, little chewing is necessary and acid production increases. If this effect is not counter-balanced by chewing hay or forage, the additional acid may eat into the stomach lining of the horse.

The amount of exercise can contribute to the development of ulcers. As the amount of exercise increases, there is often a change in feeding schedules, with longer periods of fasting and the feeding of less roughage. Exercise increases the time it takes for the stomach to empty, so large amounts of acid can remain in the stomach for a prolonged period of time.

Stress plays a role in causing ulcers in horses. When horses are transported long distances in trailers and undergo rigorous, sustained training, the stress is considered to be a major cause of ulcers. Stress from exercise can also decrease the amount of blood flow to the stomach, which makes the lining of the stomach more vulnerable to injury from stomach acid.

The fact that around 90% of race horses have ulcers is indicative of the stress horses face in the competitive world.

Use of medications can also lead to ulcers. Non-steroidal anti-inflammatory drugs (NSAIDs), such as phenylbutazone (Bute) and flunixin meglumine (Banamine), block the production of the chemical that decreases acid production in the horse's stomach. When that chemical is absent, acid levels reach higher levels, contributing to the development of ulcers.

Overcrowding, a warm, humid environment, poor-quality feed or an acute or chronic illness can also lead to ulcers.


Careful management is the key to preventing horses from developing ulcers. Turning horses out to graze whenever possible is one of the best preventative measures. Following a carefully prescribed regimen in the feeding of grains and concentrates and making sure that the horse is getting enough roughage also helps.

If the horse is traveling a great deal, competing in a number of events and/or living under stressful conditions, some veterinarians recommend medical intervention to keep the horse from developing ulcers. When used as a preventative, omeprazole administered at half the normal dose has been found by some upper-level riders and trainers to help maintain stomach health in their horses.

For horses that have undergone surgery or endured other stressful situations, a veterinarian may recommend omeprazole or similar treatment if the horse is to travel or begin intensive exercise.

Some horses handle changes in routine very well, while others react with varying levels of anxiety and discomfort. Unfortunately, no easy tests exist to determine whether a horse is developing ulcers or not.


Usually a veterinarian will do an endoscopy to check the horse's stomach for ulcers and also to see how severe they are. For a successful endoscopy, the horse will have food withheld for about 12 hours and won't be allowed to drink water for about 6 hours prior to the examination.

The veterinarian will insert the flexible endoscope through the horse's esophagus and into the stomach. Through the use of fiber optics, the veterinarian will be able to get a good look at the horse's stomach and make the appropriate diagnosis.

Medications and changes in horse management practices are the main components in treating equine gastric ulcers. Medications are used to decrease acid production, to buffer the acid that is produced and to protect the lining of the stomach from the effects of the acid.

Omeprazole is often considered to be the best and most useful treatment for ulcers in horses. Gastrogard is the brand name of this common medication. It comes in a paste form that is easy to administer and is given once a day.

Within the body, omeprazole works by shutting down some of the stomach cells' ability to produce large quantities of hydrochloric acid, giving the stomach time to heal. Omeprazole is the only treatment for EGUS currently approved by the FDA.

Oral antacids, such as Maalox and Mylanta, work to neutralize the stomach acid that has already been produced and are often recommended by veterinarians, although they have not been approved for use in horses by the FDA.

Antacids are effective for only a short time and a horse requires large amounts, making their use impractical in general, although their use on the day of a performance or stressful event may be beneficial.

A third type of medication used to treat ulcers is known as an H2 blocker, which competes with histamines that are naturally secreted by body tissues so that the stomach cells cannot produce acid. H2 blockers include cimetidine (Tagamet), ranitidine (Zantac) and famotidine (Pepcid AC).

Sucralfate is a protectant that helps block acid from coming into contact with the stomach lining. Unfortunately, it does not appear to be as effective on the esophageal portion of the stomach.

In addition to medications, changes in horse management are usually necessary. Increasing the amount of roughage in the diet, and, if at all possible, giving the horse more grazing time is important.

Increasing the number of feedings so that the horse is eating hay or pasture forage at least three or more times a day is recommended.

Avoiding or decreasing the amount of grain is important in the case of most horses. Supplements containing needed vitamins and minerals, with vegetable oils to add calories if necessary, are important recommendations for most horses.

Some veterinarians recommend giving probiotics to aid digestion, especially if the horse has a history of digestive problems.

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EquiMed staff writers team up to provide articles that require periodic updates based on evolving methods of equine healthcare. Compendia articles, core healthcare topics and more are written and updated as a group effort. Our review process includes an important veterinarian review, helping to assure the content is consistent with the latest understanding from a medical professional.