A variant form of neuronal ceroid lipofuscinosis in American bulldogs.

Neuronal ceroid lipofuscinoses (NCLs) are inherited neurodegenerative diseases characterized by accumulations of autofluorescent lipopigments within cells of the nervous system. Nine related American Bulldogs demonstrated dysmetria in all limbs and paraparesis. Nonambulatory tetraparesis was observed only in the later stages of the disease. The clinical signs developed between 1 and 3 years of age and were slowly progressive over several years, which is inconsistent with most reports in other breeds. Results from blood tests for 8 different lysosomal storage diseases on 4 affected and 6 related but unaffected dogs were negative. Four affected dogs were euthanized and histopathologic examinations showed diffuse accumulations of periodic acid-Schiff-positive inclusions in neurons and axonal spheroids along the entire neuraxis and retinae. The most severe lesions were in the brainstem proprioceptive nuclei and spinal cord, consistent with clinical signs. The storage material was autofluorescent and immunohistochemically positive for products of lipid peroxidation. Ultrastructural analysis was consistent with NCL. Pedigree analysis supports an autosomal-recessive mode of inheritance. NCL has not been previously reported in the American Bulldog and these findings suggest a variant form of the canine disease.