Polioencephalomalacia (PEM) of ruminants is a complex disease. The term indicates a morphological diagnosis where severe neuronal necrosis results in softening of cerebral grey matter. Initially though as a single disease caused by thiamine deficiency, PEM is currently believe to have several causes and different pathogenic mechanisms or a single pathogenic organism triggered by different agents are responsible for the disease. In this paper the possible causes and pathogenesis of PEM in ruminants are critically reviewed and discussed. Also are reviewed the epidemiology, clinical signs, gross and histological findings, methods of diagnosis, treatment and control.
Diseases of cattle; neuropathology; polioencephalomalacia
