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. (J Am Vet
Med Assoc 2005;227:1636–1639)