Two articles on the use of omeprazole paste (Merial’s GastroGard) in racehorses were published in the May 15 edition of the Journal of the American Veterinary Medical Association (JAVMA). The first study looked at using omeprazole paste to prevent gastric ulcers in horses entering race training. The second study looked at the efficacy of the paste to prevent the recurrence of gastric ulcers in horses in race training.

In the first study, the researchers, led by Scott R. McClure, DVM, PhD, Dipl. ACVS, of Iowa State University’s College of Veterinary Medicine, reported, “Omeprazole administered at a dosage of 1 mg/kg every 24 hours for 28 days was effective for prevention of gastric ulcers in horses starting race training.” An interesting note was that only four of 39 horses (10%) treated with a sham product (containing no omeprazole) were ulcer-free compared to 31 of 38 horses treated with omeprazole (82%).

The second study included many of the same researchers and again was headed by McClure. The researchers found that “Omeprazole oral paste administered at a dosage of 1 mg/kg every 24 hours for 28 days was effective for prevention of recurrence of gastric ulcers in horses in race training.”

Researchers noted that, “Sham-dose-treated horses and horses receiving 0.5 mg of omeprazole/kg had significantly higher ulcer scores (more and/or more severe ulcers) than did horses receiving 1 mg of omeprazole/kg.” They also reported a “significant difference” in how many horses remained ulcer-free comparing omeprazole-treated and sham-treated groups. In the treated group, 38/48 horses (79%) remained ulcer-free, and only 7/44 (16%) of the untreated group remained ulcer-free.

In the first study, the researchers said that while administration of omeprazole in previous studies has not shown a short-term enhancement of performance, “because of the reported effects of chronic ulceration on feed intake, performance, and hematologic (blood) values, it is reasonable to expect that horses without gastric ulcers would be more competitive than those with chronic severe gastric ulceration