Canine giant axonal neuropathy.

The clinical and pathological details of a case of canine giant axonal neuropathy are presented. An 18-month-old alsatian had hind leg ataxia, weakness, hypotonia and loss of patellar reflexes. Electrophysiological studies demonstrated denervation of the distal hind leg muscles and abnormal nerve conduction velocities. Biopsy and post mortem examination of the peripheral nervous system (PNS) demonstrated large anoxal swellings, up to 28mu in diameter. Electron microscopy showed these swellings to be composed almost entirely of neurofilaments. Similar giant axons were found in the central nervous system (CNS) and the distribution of the lesions in the CNS and PNS was suggestive of a 'Dying Back' disease. The possible aetiology of this new canine condition is discussed.