A CANINE ENCEPHALOMYELOPATHY WITH MORPHOLOGICAL ABNORMALITIES IN MITOCHONDRIA

A progressive encephalomyelopathy of insidious onset affecting a 16-mo nth-old dog is described. Clinically, the dog was ataxic, stumbled int o objects and showed mild behavioral abnormalities. Light microscopic findings included profound degeneration and astrogliosis of the optic pathways, loss of Purkinje neurons, focal bilateral and symmetrical br ain stem spongiosis and diffuse neuroaxial astrogliosis with swollen a nd abnormally shaped nuclei. Ultrastructurally, there were giant and b izarre mitochondria within neuronal perikarya and axons as well as dif fuse loosening of the cerebral and cerebellar neuropil. These neuropat hological findings resemble the mitochondrial encephalomyopathies of m an.