Prevalence, anatomical distribution and risk factors associated with equine gastric ulceration syndrome in American Quarter Horses Gastric ulceration is a common problem in horses

Abstract

The prevalence of equine gastric ulcer syndrome (EGUS) varies with breed, use, training and localization of the lesions between 11 % and 100%. Affected horses often show unspecific or no clinical signs. Most studies examined gastric ulceration in Thoroughbred racehorses. In this study, American Quarter Horses (AQH), which are not only used differently than Thoroughbreds but also have a different character, were examined. The aim of this study was to identify prevalence, localizations, and severity of the lesions in the gastric mucosa as well as risk factors for EGUS regarding management and feeding. The 48 study participants were examined clinically and underwent gastroscopy in their home stable. They were clinically healthy and did not receive any medication during the study period. A second examination of all horses alter 6 months was planned, but only 38/48 horses were available for follow up. Gastric ulceration was scored from 0-4 as described by Andrews et al. (1999b) and as recommended by the Equine Gastric Ulcer Council (EGUC). An ulceration score of ≥ 2 was regarded as being clinical significant. As this system does not classify the ulceration of the glandular, a scoring system with five grades (CM) was developed. Owners or caretakers provided additional information on management, training, feeding, as well as character of the respective horse. Alterations of the squamous mucosa were found in 79% of which 57% were regarded as clinically relevant and ulceration of the glandular mucosa was observed in 59% of the examinations. Both lesions of the glandular ond nonglandular parts of the stomach were observed in 43% of the examinations. Ulceration was found at the lesser curvature (56%), the nonglandular port of the margo plicatus (53%), the pylorus (48%), and the cardia (29%). Lesions in the saccus cecus and the esophogus were not observed. Alterations of the squamous mucosa were graded as 2 in 40% of the cases, 1 7% of the horses had more severe lesions. Findings of the glandular mucosa were scored with 1 in 40% of the examinations, 20% of the cases were scored as 2 or 3. In total, the alterations in the squamous mucosa were scored higher than the lesions in the glandular mucosa. Female horses were less often affected than male horses (p = 0.019). Horses housed in the country had a lower risk for EGUS than horses kept near or in cities. If the horses were housed in a city, the risk for EGUS increased significantly. Free access to fibrous feed and hay fed as the first meal of the day reduced the morbidity rate. Horses in active western performance had a higher morbidity rate than horses that did not take part in competitions (p = 0.029). The data of performance horses in this population were analyzed separately because of the great relevance on performance for this disease. A high starch intake, a status as a .,friend", a friendly character and performance in pleasure or horsemanship/showmanship events raised the morbidity rote. A calm temperament of the horses reduced the morbidity rate. Overall, the prevalence of gastric ulceration in the study population was 57% which is in the range of published data for sport and recreational horses. However, it was well above formerly reported prevalence of 40% determined for competing AQH. The assumed risk factors for EGUS were also found in the examined AQH population. Feeding roughage, pasture turnout ond housing in the country for example lowered the frequency of alterations of the gastric mucosa. Training and participation in competitions raised morbidity. In this study, fewer risk factors for the glandular mucosa than for the squamous mucosa were identified. Particularly, social aspects such as a friendly character, social status as a "friend" and time spent in human contact were associated with the severity of gastric ulceration. As a result from this study, the influence of social aspects on the gastric mucosa is of particular note. A friendly character, the social status of a friend and an increasing time spend in contact with humans were associated with the ulcer grade. This is a new approach to the pathogenesis of equine gastric ulceration and warrants further research.