Camelidae and Cervidae Polioencephalomalacia Study Guide

Overview and Clinical Importance

Polioencephalomalacia (PEM), also known as cerebrocortical necrosis (CCN), is a significant neurological disease affecting ruminants and pseudoruminants worldwide, including camelids (llamas, alpacas) and cervids (deer, elk, moose). The term derives from Greek: polio (gray), encephalo (brain), and malacia (softening), describing the pathological softening of the cerebral gray matter.

PEM is characterized by acute to subacute neurological dysfunction resulting from laminar necrosis of the cerebral cortex. The condition is most commonly associated with thiamine (Vitamin B1) deficiency or sulfur toxicosis, though multiple etiologies can produce similar clinical and pathological presentations.

Etiology and Pathophysiology

Thiamine Deficiency Mechanism

Thiamine (Vitamin B1) is an essential cofactor for key enzymes in carbohydrate metabolism, particularly transketolase in the pentose phosphate pathway and pyruvate dehydrogenase in the Krebs cycle. The brain is highly dependent on glucose metabolism, making it exceptionally vulnerable to thiamine deficiency.