Juvenile-onset neuronal ceroid-lipofuscinosis in Rambouillet sheep.

Abstract

Two, 8-month-old Rambouillet half-sister ewes with signs of visual loss and decreased mentation were examined. Ewe No. 1 was necropsied at 10 months of age, and after being held under observation for a further 6 months, ewe No. 2 was necropsied at 16 months of age. At that time, the ewe was blind and severely depressed. Both ewes had deposition of an autofluorescent lipopigment, identified as ceroid-lipofuscin, in neurons of the brain, spinal cord, eye, and dorsal root ganglia. The disease process was progressive and characterized by deposition of lipopigment with neuronal degeneration and severe fibrillary astrogliosis. This progressive loss of neurons in the older ewe led to severe retinal degeneration. No pigment was observed in cells outside of the nervous system and eye. Controlled breeding studies have shown that this disease has an autosomal, recessive inheritance. The disease referred to here as juvenile-onset neuronal ceroid-lipofuscinosis of Rambouillet sheep is unlike the majority of the hereditary ceroid-lipofuscinoses that occur in human beings and animals in that only the nervous system is affected. Therefore, this disease could serve as an excellent model for the study of lipopigment deposition that affects the nervous system as a result of various disease states and during aging.