Transmissible mink encephalopathy. Reduced spongiform degeneration in aged mink of the Chediak-Higashi genotype.

Mink which are 18 months or older and are dying of transmissible mink encephalopathy (TME) have been found to have a marked reduction in spongiform degeneration of the brain if they are homozygous for the Aleutian gene and thus exhibit the autosomal recessive disorder known as the Chediak Higashi (CH) syndrome. CH mink younger than 1 year, and young or old non-CH mink have a typical lesion profile with widespread microvacuolation of the neuropile. Whereas aged CH mink have reduced spongiform degeneration at both the light and electron microscopic level, there is no other apparent alteration in the TME disease process. The length of incubation, clinical signs, astrocytic response, and brain concentration of the TME agent are comparable to those seen in non-CH mink. We conclude that spongiform degeneration is a secondary change in TME and speculate that vacuolation may be the result of lysosomal enzymes causing an increase in ganglioside catabolism.