Effect of gastric ulceration on physiologic responses to exercise in horses.

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 post-training data) and treatment (nonulcer and ulcer groups) for mass-specific maximal O(2) consumption ([Formula: see text]O(2max)/M(b)) and mass-specific maximal CO(2) production ([Formula: see text]CO(2max)/M(b)). Post hoc analysis revealed a difference between groups for [Formula: see text]O(2max)/M(b) at day 56. Within-group differences for [Formula: see text]O(2max)/M(b) and [Formula: see text]CO(2max)/M(b) 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.