Leigh syndrome (Alaskan Husky encephalopathy, subacute necrotizing encephalomyelopathy) is a rare hereditary and rapidly fatal neurological disease characterized by necrosis and cavitation of the brain.
This disease often affects multiple dogs from the same litter.
Clinical signs usually appear at 2 - 7 months of age with rapidly progressive central vestibular neurological signs such as ataxia, circling and seizures as well as behavioral abnormalities, blindness, facial hypalgesia and difficulties in prehension of food.
Blood tests frequently reveal elevated lactate levels and lactate:pyruvate ratio, suggesting a defect in the respiratory chain.
Imaging studies such as MRI should reveal bilateral cavitation extending from the thalamus to the medulla, with less pronounced degenerative lesions in the caudate nucleus, putamen and claustrum.
On postmortem examination, most lesions involve the thalamus, with widespread involvement microscopically in basal nuclei, midbrain, pons, and medulla. These pathological changes appear similar to the striatonigral and cerebello-olivary degeneration observed in Kerry blue terriers. These dogs show clinical signs as early as 9 weeks, with lesions involving microcavition of the caudate nucleus and olivary nucleus, with degeneration in the cerebellar cortex, including severe loss of Purkinje cells, followed by degeneration in substantia nigra.
Histopathological findings in Leigh syndrome include neuronal loss with concomitant neuronal sparing, spongiosis, vascular hypertrophy and hyperplasia, gliosis, cavitation and transient mixed inflammatory infiltration. Neuronal sparing in conjunction with apparently transient astrocytic vacuolation point to the possible pathogenetic role of astrocytes in the evolution of these lesions.
A differential diagnosis would include thiamine deficiency, Afghan hound hereditary myelopathy, neonatal encephalopathy, L-2-hydroxyglutaric aciduria, striatonigral and cerebello-olivary degeneration in Kerry blue terriers and familial cerebellar abiotrophy in Bull Mastiffs.
There is no known treatment for this condition and most affected canine patients succumb to illness or require euthanasia.
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