Shetland Sheepdog leukodystrophy.

Three litters of Shetland Sheepdog pups born to the same bitch and 2 different sires were studied because of uncontrollable seizures or progressive neurologic dysfunction. Four pups from the 1st litter, 1 from the 2nd litter, and 4 from the 3rd litter had severe diffuse spongy degeneration of the white matter of the brain and spinal cord. An inherited basis for this syndrome was suspected. The purpose of this study was to evaluate the pups with currently available screening tests for the metabolic, biochemical, infectious, and toxicologic causes of leukodystrophy seen in humans and animals. Computed tomography scans revealed diffuse hypomyelination in the affected pup. Complete postmortem examination, including histopathology and electron microscopy, delineated a leukodystrophy resembling human Canavan's disease, but amino acid and organic acid metabolism abnormalities were not detected. No etiology for Shetland Sheepdog leukodystrophy has been found, but this condition represents another familial disease in the purebred dog population.