A horse suffering from ulcers isn't always easy to identify: he may have a super-shiny coat and be completely sound, but his discomfort may show in other ways, like being reluctant to be tacked up or not performing up to his potential.
Ulcers in horses are often treated with oral omeprazole. Toward the conclusion of treatment, the dose the horse receives is often tapered, but rebound gastric hyperacidity (RGH) may occur after the omeprazole treatment is concluded. This can sometimes lead to the recurrence of ulcers within days to weeks of termination of treatment.
A recent study, led by Dr. Bethanie Clark of the School of Agriculture and Food Sciences, University of Queensland in Australia, used 14 retired Thoroughbred racehorses that were being treated with omeprazole to monitor them for RGH at the conclusion of their 57-day treatment. The researchers monitored the changes in serum gastrin and chromogranin A for the study.
The horses were not actively racing, but were used as mounts for aspiring jockeys. Each horse was between 8 and 14 years old, and was fed timothy and alfalfa hay, a commercial complete feed, and rice bran.
Each horse received 4.4 to 5.3 mg/kg of omeprazole before being fed on days 1 to 61. This is double the recommended treatment dose.
The scientists performed gastroscope exams on each horse on day 0, 28, 31, 49 and 62. Omeprazole interferes with the feedback loop between the hormone gastrin and gastric pH to suppress acid production. When omeprazole is removed, the high levels of gastric again stimulate acid production, the amount of which often doubles within one to two weeks. This is the rebound gastric hyperacidity (RGH) that causes the recurrence of ulcers in 83 percent of horses within three days of having omeprazole treatment terminated.
From their study, the researchers concluded that tapering omeprazole may be unnecessary. They recommend that targeted management practices, such as increasing forage intake, resting or decreasing exercise for the two to four days after the discontinuation of omeprazole, be instituted. They also recommended that there be limited use of non-steroidal anti-inflammatory drugs (NSAID's), which also play a role in gastric ulcer disease.
Read more at EquiManagement.
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