RESUMO
Gastroduodenal ulceration is found in 90% of Thoroughbred race horses. The clinical and economical importance of gastric ulcers and the scarce information about the subject in Brazil make this investigation essential. The aim of this study was to evaluate and map grossly and microscopically the gastroduodenal lesions in race horses according to the Updated Sidney System and the Equine Gastric Ulcer Syndrome Council (EGUSC) Classification. Necropsy was performed in 14 horses and macroscopy was described. Samples of the gastric regions (14 animals - nonglandular fundus, glandular fundus, margo plicatus, antrum and pylorus) and duodenum (9 animals) were obtained and processed for routine histopathology. Macroscopic evaluation of the lesions based on the Updated Sidney System showed that 100% of the horses had gastric ulcers or erosions, mainly located at the margo plicatus. The Updated Sidney System also allowed a macroscopic gastritis classification and revealed that seven horses had enanthematous gastritis (50%), four had hemorrhagic gastritis (28, 6%), and three had erosive gastritis (21, 4%). Based on the EGUSC Classification, the most frequent score is 2 (50%). The score 3 was found in 35,7% of the horses and the scores 1 and 4 in 7,1% each. The score 0 which means intact epithelium, was not seen in any of the horses. Histopathological evaluation based on the Updated Sidney S