Peripheral neuropathy associated with malignant neoplasms in dogs.

Common peroneal and ulnar nerves of 21 dogs between 2 and 15 years of age with malignant tumors were examined for possible paraneoplastic effects. Percent of abnormalities in single-teased fiber studies exceeded the confidence limits (P = 0.99) established for age-matched control dogs in 16 of 21 dogs (76%) with malignancies, none of which manifested clinical signs of polyneuropathy. The incidence of abnormalities was higher in common peroneal nerve (73%) than in ulnar nerve (57%). Lesions were characterized by a mixture of demyelination/remyelination and axonal degeneration; however, the former lesions predominated in most affected dogs. The severity of the neuropathy varied with different tumors, with the most severe lesions observed in a bronchogenic carcinoma (59%), a mammary adenocarcinoma (59%), a malignant melanoma (48%), and an insulinoma (47%).