RESUMO
Ulcerative posthitis in bulls in Uruguay is described; 1096 bulls in 17 different establishments were examined. The incidence of bulls grazing on improved pasture was 32.9% in those under one year and 80.8% in animals of 18 to 36 months of age. Bulls grazing on natural pasture showed an incidence of 63.5% in adult animals irrespective of age. Histologic characteristics of the preputial lesions were acanthosis, parakeratosis and hyperkeratosis followed by invasion of leukocytes in the epithelium and ulceration. Corynebacterium renale was isolated from 59 of 204 prepuces. Based on the isolation of C. renale, histological lesions and the greater incidence in animals on high planes of nutrition, it is postulated that the lesion is due primarily to production of ammonia following the hydrolization of urea by the organism.