Polioencephalomalacia in ruminants from the semi-arid region of Rio Grande do Norte, Brazil

The present study aimed to describe epidemiological, clinical, laboratorial, and pathological findings of polioencephalomalacia (PEM) in ruminants from the semi-arid region of Rio Grande do Norte, Brazil. A total of seven ruminants (five sheep, one cattle, and one goat) with pathological diagnosis of PEM were included. Four cases were associated with thiamine deficiency, on account of chronic ruminal acidosis caused by diets rich in carbohydrate, with mainly concentrates, ground soybean hulls, and melon. Three ruminants from an outbreak of petroleum poisoning presented macro and microscopic lesions consistent with changes of malacia and edema in deep structures of the brain, as described in ruminants with PEM associated with sulfur intoxication. Major macroscopic changes included congestion of cerebral vessels, edema, and herniation of the cerebellum. The most observed microscopic lesions, among all assessed cases, were laminar and segmental neuronal necrosis at different regions of the brain, spongiosis, nuclear pyknosis, and red nucleus neurons. Cerebrospinal fluid analysis revealed nonspecific alterations, requiring its association with epidemiological, clinical, and pathological findings, as the results described here are similar to those reported in toxic diseases with neurological manifestations, such as botulism.