The Effect of Exercise on Equine Gastric Ulcer Syndrome in the Thoroughbred and Standardbred Athlete

Thoroughbred and Standardbred horses in race training were selected at random and examined for gastric ulcers. The mucosa of the stomach was examined by endoscopy and was scored for ulcers on a scale of 0 (no ulcers, normal mucosa) to 3 (severe ulceration with at least five deep lesions). A total of 79 horses were examined; 37 of these horses had one to four follow-up examinations, and 42 horses had only an initial gastroscopic examination. On the first examination, 33 of 79 (42%) horses had normal mucosa (ulcer score = 0), and 22 of 79 (28%) had ulcers with an ulcer score of 2 or greater. Seven horses (9%) had severe gastric ulceration (ulcer score = 3). The average ulcer score for all 79 horses on initial examination was 1.1 and 1.2 for the 37 horses with follow-up gastroscopic examination. Males (including male castrates) had slightly higher ulcer scores (1.2) than females (1.0), and 2-year-old horses had lower ulcer scores (0.7) than horses older than 3 years (1.4), but these differences did not reach statistical significance. Each of these average scores was significantly (P < .05) greater than zero. For the 37 horses with follow-up examinations, the males had higher scores (1.6) than females (0.7), and 2-year-old horses had higher ulcer scores (1.0) than 3-year-old horses (0.7) and lower ulcer scores than horses older than 3 (1.8), which were statistically significant. Follow-up examinations revealed ulcer scores ranging from 0 to 3; 23 of 37 (63%) horses had an ulcer score of 2 or greater, and 4 of 37 (12%) horses had severe ulcer disease. Average ulcer scores were significantly higher at subsequent examinations than at the initial examination. Risk of gastric ulceration increases with the length of time horses are in race training.