29 Exercise effects on equine gastric ulcer severity, inflammation, and oxidative stress

Abstract

Epidemiological evidence links exercise intensity to gastric ulcers. Eight long yearlings were used to test the hypothesis that increasing exercise intensity increases ulcer severity, inflammation, and oxidative stress. Horses fed the same diet were assigned to an unexercised control (CON) or exercised treatment group (EX; 5 d/wk on an exerciser). The study had 5 2-wk periods: acclimation (P1), light exercise (P2), moderate exercise (P3), heavy exercise (P4), and deacclimation (P5). Gastroscopies were performed on d 1 of P1 (P0) and d 14 of each period. Squamous and glandular ulcers were scored 0–4. The average (AVG) and highest (HI) score within regions were recorded. Blood samples were collected at study start and d 10 of each period. Plasma haptoglobin (Hp), serum amyloid A (SAA), malondialdehyde (MDA), and total antioxidant (TA) concentrations were determined using ELISA and colorimetric assays. Data with normally distributed residuals were analyzed with a mixed ANOVA and horse as a random effect to determine effects of treatment, period, and interactions. Data with non-normal residuals were analyzed with a Kruskal-Wallis and Dunn's test. Significance was set at P < 0.05 and trends at P < 0.1. No effect of exercise was detected on ulcer severity. No period effects were detected for glandular ulcers. There was a period and treatment x period interaction for AVG squamous scores (P = 0.04, P = 0.05; respectively) and a period effect for HI squamous scores(P = 0.06) (Table 1). The highest squamous ulcer scores were detected at P0, when horses entered the study after being previously maintained on pasture. The P1 Hp (1.63 mg/ml) was higher than P3 (1.25 mg/ml) and P5 (1.06 mg/ml). The CON SAA was higher than EX (χ2(1) = 4.68, P = 0.03) and trended higher for MDA (χ2(1) = 3.27, P = 0.07). Moderate exercise seemed to improve inflammatory and oxidative status. Research using larger sample sizes is needed to clarify effects of exercise on ulcers.