54 Evaluation of gastric health in cribbing horses fed a digestive support supplement

Cribbing is a stereotypic oral behavior whereby the horse places its incisors on a fixed object, arches its neck, pulls against the object, and emits an audible grunt. Cribbing behavior (CB) has been associated with gastrointestinal (GI) dysfunction and gastric ulceration. This randomized crossover study tested the hypothesis that dietary inclusion of a commercially available equine GI support supplement (Legends Gastrocare, Cargill, Wayzata, MN) would alter the GI environment and gastric ulcer severity in normal and cribbing horses. Mature Quarter Horses with CB (n = 4) and sex-matched non-cribbing controls (NCB; n = 4) were randomly assigned to receive either a GI support supplement (TRT) or placebo for 21 d, followed by a 2-wk washout period. Treatment groups were then switched and horses were treated for an additional 21 d. Before and after each treatment period, gastric and fecal pH were measured, and gastric ulcer severity was evaluated via endoscopic examination using an established grading system for squamous (0–4) and glandular gastric ulceration (0–1). Horses were acclimated for 2 wk before the start of the study, and throughout the study were individually stalled 16 h/d and fed bermudagrass hay (1.2% BW, DM basis) and concentrate (0.5% BW) and turned out in pairs in paddocks 8 h/d. Data were analyzed by mixed-model ANOVA with treatment, cribbing status (CB or NCB) and period included as fixed effects, and horse as a random effect. Data are presented as means ± SD. Fecal pH (6.5 ± 0.1) and gastric pH (2.9 ± 0.5) were similar between CB and NCB horses and were unaffected by TRT. Squamous mucosa ulcer scores did not differ between CB and NCB, and were unaffected by TRT. However, within CB horses, squamous ulcer severity scores were greater (indicating more severe ulceration) (P = 0.003) with TRT (3.9 ± 0.6) than placebo (1.4 ± 0.3). Based on this pilot study, administration of a commercial GI support supplement did not alter gastric or fecal pH in normal or CB horses. Ongoing serum cortisol, serum gastrin, and microbiome analyses may help to explain the differences in gastric ulceration severity noted in CB horses when receiving TRT versus placebo. Collectively, these findings add to the growing body of literature regarding GI environment and pathophysiology in horses exhibiting CB.