Peripheral nerve pathology in two rottweilers with neuronal vacuolation and spinocerebellar degeneration.

Neuronal vacuolation and spinocerebellar degeneration in young Rottweiler dogs is a neurodegenerative condition characterized by neuronal vacuolation of several nuclei in the central nervous system and degeneration of the spinal cord white matter. Here, we describe the morphologic and ultrastructural findings in laryngeal muscles and peripheral nerves of a 16-week-old female and a 32-week-old female Rottweiler dog affected by progressive ataxia and tetraparesis associated with laryngeal paralysis. Lesions were characterized by neurogenic muscle atrophy of the intrinsic laryngeal muscles, and a loss of large myelinated fibers in the recurrent laryngeal nerve, accompanied by demyelinating/remyelinating features affecting the small myelinated fibers. No significant changes were detected in the cranial laryngeal, vagus, phrenic, ulnar, or peroneal nerves. These findings were indicative of a selective distal neuropathy of the recurrent laryngeal nerve with early severe axonal degeneration, mainly of the large myelinated fibers.