Cerebellar vermian hypoplasia in dogs.

Six dogs with cerebellar dysplasia, in which the cerebellar vermis was hypoplastic, are described. Clinical signs in these dogs were noted around 2 weeks of age and included ataxia, dysmetria, and intention tremors. A variable portion of the caudal cerebellar vermis was absent in each dog; portions of the cerebellar hemispheres and flocculus also were absent in some of them. Neurons in certain brain stem nuclei that project to the cerebellum were either chromatolytic or vacuolated. Cerebellar vermian hypoplasia of dogs is analogous to the Dandy-Walker syndrome of human beings.