RESUMEN
Nine adult female Balady sheep [8-9 months old] were divided into 3 equal groups. Gp.1 was fed on a balanced diet containing 0.8% elemental sulfur, Gp.2 was fed on the same diet with 0.8% sulfur plus 0.025% pure thiamine, and Gp.3 was a control. Feeding on these diets continued until the appearance of neurologic signs which only appeared in GP.1 and started as anorexia and ended up with coma. Three animals from Gp.1 were dying on days 25, 26 and 28 of the experiment. Brain lesions of Gp.1 animals were typical of polioencephalomalacia [PEM] Primarily of the cerebral and to some extent of cerebellar cortices; however, similar lesions were restricted only to the cerebral grey matter in animals of Gp.2 despite absences of any signs of illness. The extraneural lesions were noticed in animals of Gps. 1 and 2 and included periportal necrosis, serofibrinous pneumonia, renal tubulonecrosis, myocardial segmental necrosis and lymphocytic cell depletion of the splenic corpuscles. It was evident that simultaneous supplementation of thiamine [0.025%] with excess sulfur [0.8%] only prevented the appearance of clinical signs associated with PEM despite the occurrence of the classic cerebral lesions. Also, the neural lesions were confined only to the cerebrum; however, the cerebellum was normal. Moreover, administration of thiamine did not prevent the appearance of extraneural lesions