The study was performed to evaluate the efficacy of
omeprazole powder in sterile water, administered intravenously, on gastric juice pH in adult horses with naturally occurring
gastric ulcers.
Omeprazole (0.5 mg/kg, IV) was administered once daily for 5 days to 6 adult horses with
gastric ulcers. Gastric juice was aspirated through the biopsy channel of an
endoscope and pH was measured before and 1 hour after administration of
omeprazole on day 1, and then before and after administration of
omeprazole on day 5.
Gastric ulcer scores were recorded on day 1 before administration of
omeprazole and on day 5, 23 hours after the 4th daily dose. Gastric juice pH and
ulcer scores were compared between the times. When compared with the pre-injection value (2.01 +/- 0.42), mean +/- SD gastric juice pH was significantly higher when measured 1 hour after administration of the initial dose (4.35 +/- 2.31), and before (5.27 +/- 1.74) and 1 hour after (7.00 +/- 0.25) administration of
omeprazole on day 5. Nonglandular
gastric ulcer number score significantly decreased from a mean +/- SD of 3.2 +/- 0.80 to 2.0 +/- 1.1, but nonglandular
gastric ulcer severity score remained the same. Few glandular
ulcers were seen in the study, and scores did not change. Because of its potent and long duration of action on gastric juice pH, this intravenous formulation of
omeprazole may show promise for treatment of equine
gastric ulcer syndrome (EGUS) in horses with
dysphagia, gastric reflux, or other conditions that restrict oral intake of
omeprazole paste. Aspiration of gastric juice and measurement of pH can be of use to determine whether the desired pH > 4.0 has been reached after
omeprazole treatment.