Preventing Gastric Ulcers: Study

"Gastric ulcers are a widespread and significant problem," said Gary W. White, DVM, of Salisaw Equine Clinic in Salisaw, Okla., at the 2003 American Association of Equine Practitioners' convention. "Omeprazole (Gastrogard) is FDA-approved for the treatment of gastric ulcers in horses and foals greater than four weeks old at 4 mg/kg/day," he said, adding that reports had suggested that doses lower than 2 mg/kg/day (a dose already proven to prevent recurrence of ulcers) might be effective in preventing the development of gastric ulcers.

White and 10 other veterinarians from private and university equine hospitals in the United States and Canada investigated whether a dose of 1 mg/kg/day would prevent occurrence and recurrence of gastric ulcers in racehorses. A total of 285 horses (including Thoroughbreds, Quarter Horses, and Standardbreds) were used to confirm the dose required to stave off ulcer occurrence and prevent recurrence. "The dorsal portion of the stomach becomes highly acidic during exercise," said White. "During the study period, these horses were maintained in active race training and were allowed to race, so that they were maintained under strong ulcerogenic conditions."

Prevention of equine gastric ulcer syndrome (EGUS) was evaluated in confirmed ulcer-free horses which were going into race training. Horses already racing or in race training with ulcers were evaluated after they underwent omeprazole treatment at 4 mg/kg/day for 28 days (the dose shown to heal ulcers) to find out the prevention of recurrence with omeprazole. All horses were scoped and their stomach linings were graded before prevention treatments (as a baseline) and again after 28-30 days of preventive treatments.

To select the dose, veterinarians compared the effects of orally administered omeprazole paste and a sham-dose (an empty tube used in the control group) at 0.5, 1.0, or 2.0 mg/kg/day for 28 days. In these trials, they found that the 1.0 mg/kg/day dose of omeprazole was more effective in preventing recurrence of ulcers than either the sham or 0.5 mg/kg/day doses. In the prevention of the occurrence of ulcers, the 1.0 mg/kg/day dose was more effective than the sham dose, and the effect did not differ significantly from the 2.0 mg/kg/day dose.

In dose confirmation studies, veterinarians compared the effects of sham-dose and omeprazole paste at 1.0 mg/kg for 28 days. Combining data from the dose selection and confirmation studies, gastric ulcers developed in 86% and 82% of horses receiving the sham dose. White said, "This shows the studies were designed so the horses were under intense ulcerative pressure."

Only 18% of horses receiving the 1.0 mg/kg/day dose had ulcers develop, showing that the dose provided 82% prevention of occurrence. Ulcers recurred in only 19% of cases, showing 81% prevention of recurrence.

"Subjectively, we believed they did better and performed better (on omeprazole)," said White. "All of us have had the experience of treating horses that haven't had overt physical signs, but improve in performance and attitude as we heal up the gastric ulcers."

He summarized, "Omeprazole can be administered at an oral dose of 1 mg/kg/day. Ulcer prevention was demonstrated under ulcerogenic conditions, and we found that higher doses and loading doses don't seem to enhance the prevention or recurrence."

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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