Ovine and Caprine Polioencephalomalacia Study Guide
Overview and Clinical Importance
Polioencephalomalacia (PEM), also known as cerebrocortical necrosis (CCN), is a common, potentially fatal neurological disease affecting sheep and goats worldwide. The term "polio" in this context refers to gray matter (Greek: polios = gray), "encephalo" refers to brain, and "malacia" means softening. This disease has absolutely no relationship to the viral poliomyelitis affecting humans.
PEM is characterized by necrosis of the cerebral cortex, leading to neurological dysfunction. In small ruminants, the disease often has a shorter course with fewer survivors compared to cattle, making early recognition and treatment critical. Mortality rates range from 50-90% if untreated.
Etiology and Pathophysiology
Primary Causes
PEM is a pathological diagnosis representing the common endpoint of several conditions. The two primary mechanisms are:
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