Effects of treatment with omeprazole or ranitidine on gastric squamous ulceration in racing Thoroughbreds.

Objective: To compare the effects of oral administration of omeprazole and ranitidine on gastric squamous ulceration in Thoroughbreds in race training.

Design: Modified crossover study.

Animals: 60 Thoroughbreds in race training with gastric squamous mucosal ulceration.

Procedure: Horses were randomly allocated into 3 groups. Group 1 received no treatment for 28 days followed by administration of omeprazole (4 mg/kg [1.8 mg/lb], PO, once daily) for 28 days; group 2 received omeprazole (4 mg/kg, PO, once daily) for 28 days followed by no treatment for 28 days; and group 3 received ranitidine (6.6 mg/kg [3.0 mg/lb], PO, q 8 h) for 28 days followed by administration of omeprazole (4 mg/kg, PO, once daily) for 28 days. Ulceration was assessed endoscopically at days 0, 28, 42, and 56. Lesions were scored from 0 (no ulceration) to 3 (severe ulceration).

Results: After the initial 28 days of treatment, the decrease in ulcer severity was significantly greater after omeprazole treatment than after ranitidine treatment. Ulcer severity decreased significantly in group 3 horses after 14 days of treatment with omeprazole. Discontinuation of omeprazole resulted in worsening of ulcer scores; however, ulcer scores at completion of the study were less than at day 0. Horses that received omeprazole after 28 days of ranitidine treatment had a further reduction in ulcer severity.

Conclusions And Clinical Relevance: Omeprazole was more effective than ranitidine in healing gastric squamous ulcers in Thoroughbreds in race training. Improvement was detected by 14 days and persisted in most of the group 2 horses for at least 28 days after omeprazole treatment was discontinued.