The gross and histopathological findings in the brain and spinal cord of fi
ve Alaskan Husky dogs with a novel incapacitating and ultimately fatal fami
lial and presumed hereditary neurodegenerative disorder are described. Four
dogs presented with neurological deficits before the age of 1 year (7-11 m
onths) and one animal at 2.5 years old. Clinical signs in all dogs were of
acute onset and included ataxia, seizures, behavioral abnormalities, blindn
ess, facial hypalgesia and difficulties in prehension of food. Tn animals a
llowed to survive, the disease was static but with frequent recurrences. Pa
thological findings were limited to the central nervous system. Grossly vis
ible bilateral and symmetrical cavitated foci were consistently present in
the thalamus with variable extension into the caudal brain stem. Microscopi
c lesions were more widespread and included foci of bilateral and symmetric
al degeneration in the basal nuclei, midbrain, pens and medulla, as well as
multifocal lesions at the base of sulci in the cerebral cortex and in the
gray matter of cerebellar folia in the ventral vermis. Neuronal loss with c
oncomitant neuronal sparing, spongiosis, vascular hypertrophy and hyperplas
ia, gliosis, cavitation and transient mixed inflammatory infiltration were
the main histopathological findings. Tn addition, a population of reactive
gemistocytic astrocytes with prominent cytoplasmic vacuolation was noted in
the thalamus. Lesions of this nature in this distribution within the neuro
axis have not been reported in dogs. The neuropathological findings resembl
e Leigh's disease/subacute necrotizing encephalomyelopathy of man. Neuronal
sparing in conjunction with apparently transient astrocytic vacuolation po
int to the possible pathogenetic role of astrocytes in the evolution of the
se lesions. An inherited metabolic derangement of unknown nature is postula
ted as the cause of this breed-specific disorder.