polyneuropathy in dogs and cats is a collection of peripheral nerve disorders that often are breed-related in these animals. polyneuropathy indicates that multiple nerves are involved, unlike mononeuropathy. polyneuropathy usually involves motor nerve dysfunction, also known as lower motor neuron disease. symptoms include decreased or absent reflexes and muscle tone, weakness, or paralysis. it often occurs in the rear legs and is bilateral. most are chronic problems with a slow onset of symptoms, but some occur suddenly.