Presumed immune-mediated cerebellar granuloprival degeneration in the Coton de Tuléar breed

An unusual form of cerebellar granuloprival degeneration was observed in three male Coton de Tuléar puppies between 12 and 14 weeks of age from different litters showing progressive cerebellar signs beginning at 8 weeks after birth. Pathological examinations revealed a shrunken cerebellum. Histopathologically the granular cells were diminished or almost completely absent, some 'torpedos' of Purkinje cells were present. There was a marked gliosis, and occasionally small inflammatory foci were present. A marked diffuse T cell infiltration (CD3(+) cells) occurred in the lesions, B cells did not appear. CD18 staining showed an upregulation of microglial cells at the lesion site. Histopathologically the lesions resembled paraneoplastic cerebellar degeneration which is caused by an autoimmune mediated T cell reaction. This congenital condition in the Coton de Tuléar dog breed could be based on a genetically defined immune defect leading to autoimmune destruction of the granular cells.