Equine
gastric ulcer syndrome (EGUS) is very common among performance horses, with a reported prevalence of approximately 90% in racehorses, and also > 50% in foals.
Omeprazole, an
acid pump inhibitor 5 times more potent than
ranitidine, has been used with great success to treat EGUS. This multicentre study of Thoroughbred racehorses with endoscopically verified
gastric ulcers was designed to demonstrate the efficacy of an equine oral
paste formulation of
omeprazole in the treatment and prevention of recurrence of EGUS. Of the 100 horses entered into the study, 25 were
sham-dosed for the full 58 days of the study. The remaining 75 horses all received
omeprazole paste, 4 mg/kg bwt/day once daily for 28 days. At Day 28, 25 of treated horses continued on this dosing regimen while 25 received a half dose (2 mg/kg bwt once daily) and 25 horses were
sham-dosed. By Day 28,
gastric ulcers were completely healed in 77% of
omeprazole-treated horses, while 92% were significantly (P < 0.01) improved. In contrast, 96% of the
sham-dosed horses still had
gastric ulcers at Day 28. The improvement was maintained in horses that continued on either a full dose or half dose of
omeprazole paste until Day 58. However, in those horses that were removed from
omeprazole treatment at Day 28, the incidence and severity of the
gastric ulcers at the end of the study were similar to those horses that did not receive the
omeprazole paste. This study demonstrates that
omeprazole paste, 4 mg/kg bwt per os, once daily, is highly effective in healing
gastric ulcers in Thoroughbred racehorses and that either a full dose or half dose of
omeprazole paste effectively prevents the recurrence of EGUS. The study also indicates that
gastric ulcers in untreated horses did not demonstrate a significant rate of
spontaneous healing.