Diagnosing Equine Gastric Ulcers

By Alfredo Sanchez-Londoño, MV, MS

Equine gastric ulcer syndrome, also known as EGUS, is a fairly common disease that can affect up to 90 percent of racehorses in active training and 60 percent of show horses. Gastric ulcers are a result of damage to the lining of the stomach due to prolonged exposure to the normal acid present there. Unlike humans, horses secrete acid continually, which can result in an excessive amount of acid if the horse is not eating regularly and there is no feed to neutralize it. Unfortunately, with domestication of the horse and feed practices that include just twice-a-day feedings of large amounts of grain, the stomach will have an increased accumulation of acid that will damage the mucosa (lining) of the stomach.

The horse’s stomach has two different portions—one is the glandular portion (located in the bottom of the stomach), and the other is the non-glandular portion (in the top portion). The thick band dividing these two portions is called the margo plicatus. The glandular portion is responsible for secretion of acid and has a protective coating that will prevent it from being damaged. The non-glandular portion is designed to mix the stomach content and does not have as much protection from the acid, making it more prone to development of ulcers.

Ulcers in horses have been attributed to stress, which include race training, long distance transportation, surgery, medications and underlying diseases, among others. Prolonged administration of non-steroidal, anti-inflammatory drugs such as phenylbutazone can decrease the production of the protective mucus layer, which makes it more susceptible to development of ulcers.

Clinical signs of gastric ulcers can vary from very subtle to very serious. Most horses with ulcers will present with a history of poor appetite (especially not eating their grain), decreased performance, poor body condition, poor hair coat and changes in behavior. More serious cases can present with significant bouts of abdominal pain or colic.

Diagnosis of gastric ulcers is made through gastroscopy, which involves passing a flexible three-meter endoscope into the stomach and looking at its surface. This procedure should be done on an empty stomach (withhold feed for at least 12 hours, and water for 2-3 hours). The horse is sedated so that a complete examination of the whole stomach can be performed and the integrity of the esophagus can be evaluated. Most of the ulcers will be present at the margo plicatus, or at the non-glandular portion, and will appear as small erosions, or larger areas with evidence of bleeding.

Treatment of gastric ulcers involves the use of medications that will decrease acid production. The most commonly used drugs are omeprazole and sulcrafate. Both of these drugs serve the same purpose, but they must be used for a prolonged period of time to achieve adequate healing. In combination with administration of drugs, management changes such as allowing more time for grazing, decreasing very rich grains and decreasing stressors as much as possible should to be implemented.