horse looking through stall bars

Gastric ulcers can affect up to 60% to 90% of adult horses. Certain factors put horses at greater risk for developing ulcers (their jobs, age, living conditions, and more). While medications can help us treat and prevent ulcers in horses, eliminating or reducing inciting risk factors is an essential step in mitigating their development. Sometimes risk factors can’t be avoided, so researchers recently studied whether the medications omeprazole and sucralfate could combat them.

Equine gastric ulcer syndrome (EGUS) can cause disease, discomfort, poor performance, and other issues in horses. Under the EGUS umbrella, horses can suffer from equine squamous gastric disease (ESGD, in which ulcers develop in the upper squamous part of the horse’s stomach) and equine glandular gastric disease (EGGD, in which they develop in the lower glandular portion of the stomach). In all cases ulcers develop when acid meets the stomach lining if it’s unprotected by buffering agents.

“Risk factors for ESGD are things that increase the acidity and/or splashing of gastric contents, such as fasting, grain feeding, and intense exercise,” said Rebecca Bishop, DVM, MS, an equine surgery resident at the University of Illinois College of Veterinary Medicine, in Urbana. “We don’t have as clear an understanding of what causes ulceration in the glandular part of the stomach, but known risk factors include inflammation, non-steroidal anti-inflammatory drug (NSAID) administration, frequency of exercise, breed, and experience level of the horse.

“While exposure to known EGUS risk factors can typically be avoided in healthy horses, in our experience, ill patients often simultaneously experience multiple risk factors for EGUS, including transport, stress, fasting, and NSAID administration,” she added.

Bishop and colleagues put two common treatments—omeprazole and sucralfate—to the test to see if one was superior for mitigating gastric ulcer development in fasted horses receiving the NSAID flunixin meglumine (Banamine). Though their study subjects were healthy horses, they attempted to mirror what a sick horse might encounter during hospital admission and treatment.

During the study, horses participated in a feed-fast/NSAID protocol for seven days. They always had fresh water available and underwent three gastroscopic exams during each study period (Days 2, 4, and 7, each of which followed a fasting period) so the team could assess their ulcer scores (the higher the score, the more severe the ulcers). Horses received flunixin (1.1 mg/kg, administered intravenously) every 12 hours for five days, starting at the first gastroscopic exam and ending the night before the final one. For the same five days, horses also received either omeprazole (1 mg/kg of body weight, administered orally) daily or sucralfate (20 mg/kg of body weight, administered orally) every eight hours. Horses served as their own controls, as they received both treatments with a washout period between.

Not surprisingly, Bishop said, all study horses’ ESGD and EGGD scores increased over time during the feed-fast/NSAID protocol.

“However,” she added, “one of the surprising findings was just how quickly ulceration developed in some horses, even between Days 2 and 4 of the study.”

Following treatment, Bishop said, sucralfate-treated horses had higher ESGD and EGGD scores than omeprazole-treated horses, which suggests omeprazole was more effective at mitigating ulcer development in this scenario. Omeprazole could have had some type of protective effect on the horses’ stomachs, she said.

“Our results demonstrated that severe squamous and glandular disease developed rapidly under conditions that hospitalized equine patients may be exposed to, highlighting the importance of gastric ulcer prophylaxis in at-risk equine patients,” she said. “While sucralfate may still be useful to mitigate clinical signs in the short term, based on our findings I’m reaching for omeprazole for mitigation of EGUS in my patients that are exposed to the dual risk factors of fasting and flunixin meglumine administration.”

The study was published in the October 2021 issue of Equine Veterinary Journal.