Objective - To develop a protocol to induce and maintain gastric ulceration in horses and to determine whether gastric ulceration affects physiologic indices of performance during high-speed treadmill exercise. Animals - 20 healthy Thoroughbreds. Procedures - Each horse was acclimatized to treadmill exercise during a 2-week period. Subsequently, baseline data were collected (day 0) and each horse began an incrementally increasing exercise training program (days 1 through 56). Beginning on day 14, horses were administered omeprazole (4 mg/kg, PO, q 24 h until day 56) or no drug (10 horses/group) and underwent alternating 24-hour periods of feeding and feed withholding for 10 days to induce gastric ulceration. Extent of gastric ulceration was assessed weekly thereafter via gastroscopy. Physiologic indices of performance were measured at days 0 and 56. Gastric ulceration and exercise performance indices were compared within and between groups. Results - In untreated horses, gastric ulcers were induced and maintained through day 56. Gastric ulcer formation was prevented in omeprazole-treated horses. There were significant interactions between time (pre- and posttraining data) and treatment (nonulcer and ulcer groups) for mass-specific maximal O2 consumption (V̇O2max/M b) and mass-specific maximal CO2 production (V̇co 2max/Mb). Post hoc analysis revealed a difference between groups for V̇O2max/Mb at day 56. Within-group differences for V̇O2max/Mb and V̇co 2max/Mb were detected for omeprazole-treated horses, but not for the horses with ulcers. Conclusions and Clinical Relevance - In horses, gastric ulcers were induced and maintained by use of alternating periods of feeding and feed withholding in association with treadmill exercise (simulated racetrack training). Gastric ulcers adversely affected physiologic indices of performance in horses.
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