Understanding Your Horse's Stomach

  • Stomach – The stomach of the horse contains about 10% of the capacity of the small intestine (compared with 70% for cows). Therefore, horses cannot handle large amounts of feed and must eat frequent, small portions.
  • Esophagus – A muscular tube that carries food from the mouth to the stomach. In the horse, food only moves one way down this tube; horses cannot throw up.
  • Squamous mucosa – Covers approximately one-third of the equine stomach and is void of glands. The texture of the healthy cells in this area feel like the skin on the back of your hand. Ulcers most regularly occur in this region near the margo plicatus curvature.
  • Margo plicatus – The folded ridge of the mucous membrane between the stomach’s nonglandular portion and the glandular portion.
  • Glandular mucosa – Covers the remaining two-thirds of the stomach and contains the acid-producing glands. Ulcers are less prevalent here (but still possible) due to having more protective factors.
  • Pylorus – Lower portion of the stomach that leads into the small intestine.
  • Duodenum – Uppermost part of the small intestine that plays an important role in the digestive function. Carries partially digested food out from the stomach.
  • Acid-stimulating receptors – Trigger an “acid pump” to secrete acid. Sensitive to diet and stress.

Your horse’s stomach is relatively small and designed to continuously produce acid from millions of acid pumps – up to 16 gallons a day – to digest small, frequent meals.1 In a natural grazing scenario, grass and saliva are constantly present to buffer and help pass acid from the stomach.

When horses are stalled with limited turnout and fed fewer, larger meals, acid levels increase. Higher intake of grain and stress from training, showing and even changes in their routine can stimulate acid pumps to increase acid levels even more.2,3,4,5,6 As levels rise, acid can reach the unprotected squamous mucosa where it can eat through the lining.

The resulting stomach ulceration often suppresses appetite, so the horse may eat even less buffering roughage. This creates a vicious cycle of increased acidity. Watch.

Your veterinarian will use an endoscope, a tiny camera attached to a long, thin tube, to examine the inside of your horse’s stomach for ulcers. If endoscopy is not practical, then a presumptive diagnosis may be made based on clinical signs, history and a physical examination.

See how prevalent stomach ulcers are in your discipline.


See why equine stomach ulcers happen

Diagnosing Equine Stomach Ulcers

Endoscopy, or “scoping,” is a procedure that lets your veterinarian look inside your horse’s stomach via a tiny camera attached to a long, thin tube. Your veterinarian will place the endoscope in through the nostril, then down the esophagus and into the stomach. There, the lining can be examined for the presence of ulcers. If endoscopy is not practical, then a presumptive diagnosis may be made based on clinical signs, history and a physical examination.

What endoscopy reveals

IMPORTANT SAFETY INFORMATION: ULCERGARD can be used in horses that weigh at least 600 pounds. Safety in pregnant mares has not been determined.
CAUTION: Safety of GASTROGARD in pregnant or lactating mares has not been determined. For prescribing information click here.
*When administered for 8 or 28 days, ULCERGARD is proven to effectively prevent gastric ulcers in horses exposed to stressful conditions.
1 Kitchen DL, Merritt AM, Burrow JA. Histamine-induced gastric acid secretion in horses. Am J Vet Res . 1998;59(10):1303-1306.
2 Murray MJ. Overview of equine gastroduodenal ulceration. AAEP Proccedings . 1997;43:382-387.
3 Mitchell RD. Prevalence of gastric ulcers in hunter/jumper and dressage horses evaluated for poor performance. Association for Equine Sports Medicine. September 2001.
4 McClure SR, Carithers DS, Gross SJ, Murray MJ. Gastric ulcer development in horses in a simulated show or training environment. J Am Vet Med Assoc . 2005;227(5):775-777.
5 ULCERGARD product label.
6 Equine Gastric Ulcer Council. Recommendations for the diagnosis and treatment of Equine Gastric Ulcer Syndrome (EGUS). Equine Vet Educ . 1999;11:262-272.
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