Equine gastric ulcer syndrome is a common condition, both in performance horses, such as racehorses, and in foals. Pamela Wilkins, DVM, PhD, Dipl. ACVIM, ACVECC, an equine veterinarian at the University of Illinois Veterinary Teaching Hospital in Urbana, says more than 90% of performance horses have gastric ulcers, as do between 25 and 50% of foals.

“Ulcers are sores in the lining of the stomach,” explains Wilkins, who is boarded both in equine internal medicine and in equine emergency and critical care.

In horses, the top portion of the stomach is lined with flat non-glandular cells and the lower portion has glandular cells.

Wilkins says approximately 80% of equine gastric ulcers occur in the non-glandular upper portion, which is less resistant to injury from stomach acid. The glandular tissue is more resistant to damage because it secretes mucus