Internal hydrocephalus combined with pachygyria in a wild-born brown bear cub

Abstract

An abandoned wild-born male brown bear (Ursus arctos) cub of the year was found and subsequently placed in a zoo. At 7 months of age, the cub showed first signs of ataxia, and at 13 months of age, it was unable to move the hind legs and exhibited outbursts of aggressive behavior and self-mutilation. The animal was euthanized, and necropsy revealed alterations of the brain with obviously flattened gyri, profound enlargement of both lateral ventricles and considerable accumulation of cerebrospinal fluid, disruption of the septum pellucidum, and atrophy of the hippocampus. The animal was diagnosed with an internal hydrocephalus and pachygyria. Genetic evidence showed that the father of the described cub was also the father of the cub’s mother, suggesting the possibility of congenital hydrocephalus.