Equine Gastric Ulcers
Equine Gastric Ulcer Syndrome (EGUS) is used to describe a condition of ulceration of the lining of a horse's stomach. Gastric ulcers can affect any horse at any age, with 25 to 50 percent of foals and 60 to 90 percent of adult horses being affected. The lining of the stomach is eroded due to a prolonged exposure to stomach acids. Management and husbandry can play a large role in the development of gastric ulcers. Horses are designed to be grazers with regular intake of roughage. Since the horse's stomach continually secretes acid, gastric ulcers can result when the horse is not eating regularly. Prolonged or strenuous exercise can also increase acid content with the sensitive portions of the stomach.
The horse's stomach is divided into two parts. The lower portion is glandular region where acid and digestive enzymes are secreted- both hydrochloric acid and pepsin. There is also secretion of protective compounds, such as bicarbonate and mucus, which help coat the stomach to minimize damage from the acid. The top portion of the stomach is designed for mixing of the contents of the stomach and does not have as much protection from the acid. The junction of the two regions of the stomach is termed the margo plicatus, and this is the most common place to find gastric ulcers in many horses. Horses on NSAIDs, such as bute or banamine, may develop ulcers in the glandular region of the stomach near the pylorus. Ulcers can also extend down into the duodenum, the first segment of small intestine.
Ulcers are often a result of husbandry conditions. Stall confinement, meal feeding, and high-grain diets can all increase the likelihood of ulcers. Diets comprised of whole grains, are high in carbohydrates and cause formation of volatile fatty acids that can contribute to ulcer formation. Stress, both environmental and physical, will increase the incidence of ulcers. Standard training and showing have been shown to induce ulcers within a week's time. Hauling, stabling and changing groups of horses can be very stressful for your equine companion. Finally, chronic administration of any non-steroidal anti-inflammatory drugs such as phenylbutazone, flunixin meglumine, firocoxib or ketoprofen, can decrease the production of the stomach's protective mucus layer, making it more susceptible to ulcers.
Many horses with gastric ulcers may have clinical signs that are subtle and easily overlooked. Mild clinical signs include failure to consume a meal, dullness, attitude changes, poor appetite, decreased performance, reluctance to train, poor body condition, rough hair coat, weight loss, excessive recumbency, low-grade colic or teeth grinding.
Definitive diagnosis of ulcers is through gastroscopy. The horse is fasted for 12-24 hours and then a long endoscope is passed through a nostril, down the esophagus and into the stomach. The lining of the stomach can then be visualized and evaluated for the presence and degree of ulcerations. A presumptive diagnosis of EGUS is often made by identifying typical clinical signs, ruling out other disease conditions and by having a positive response to appropriate therapy.
Treatment of ulcers is aimed at reducing the inciting factors and decreasing acid production. Reduce confinement time by allowing access to pasture or other turnout. Evaluating relationships with other horse's is important and social groups may need to be re-arranged. Free-choice access to grass or hay provides a more natural grazing diet keeping feed in the stomach to help buffer the acid. The act of chewing also produces saliva, a natural antacid. Minimize grain feedings; feed smaller more frequent meals, and remove high carbohydrate feeds that form the volatile fatty acids. For horses that require more calories than a hay diet can supply, switch to a feed that is higher in fat and highly digestible fibers. There are many commercial diets available that fit this description. Fat calories can be added in the form of corn oil to an otherwise balanced diet. Nutritional evaluation is complex and needs to be individualized for each horse and situation.
Medication to decrease acid production may be necessary in horses showing clinical disease or when the predisposing factors cannot be removed. There are many over-the-counter products available-these are known as nutriceuticals- a nutritional supplement, not a medication, and cannot claim to treat a medical condition. Antacids are formulated to buffer stomach acid, but to be useful, they would need to be administered 6-12 times a day. Antacids administered with feeds are relatively ineffective because they are ingested at the same time as the feed, which will buffer the acid by itself. The only FDA approved medical treatment for equine gastric ulcers is GastrogardTM (Merial). GastrogardTM contains omeprazole, a proton pump inhibitor and decreases the actual production of acid within the stomach. A 28 day course of Gastrogard is typically sufficient to heal ulcers, although re-evaluation with a gastro-scope is recommended to ensure complete resolution.
Prevention of ulcers is ideal, but when this is not adequate or possible, horses at greatest risk will benefit from daily medication to decrease acid production. A lower dose of omeprazole, Ulcergard TM (Merial), is often used as a preventative measure when the horse must remain under stress or husbandry conditions that predispose them to ulcers.
Ulcers are a very important and prevalent disease in our population of horses. If you have questions regarding symptoms that your horse is having, please call your equine veterinarian. There are many conditions that can have similar signs; therefore diagnosis is the first step to getting your horse's issue resolved. Ulcers are painful, and can decrease your horse's performance as well as cause behavioral issues. Proper diagnosis, treatment and management are key to keeping your equine partner healthy and happy.
Dr. Sandra Gebhart
Willow Creek Veterinary Service
3578 Hamlin Rd. Medina, OH 44256 | 330.410.4899