An epizootic of cerebrospinal nematodiasis in cottontail rabbits.

A progressively debilitating neurologic syndrome characterized by torticollis, ataxia, circling, and abnormal posture was observed in 16 of approximately 60 cottontail rabbits (Sylvilagus floridanus) captured in a 12-hectare portion of a woodlot in southwestern Virginia. Inflammatory and degenerative alterations in cerebellum and midbrain regions were characterized principally by malacia, perivascular cuffing, and gliosis. Single Ascaris columnaris larvae were found in the cerebellum of 2 rabbits and the spinal cord of 1 rabbit.