A peripheral neuropathy is any nerve disorder that affects the peripheral nervous system. There are a number of different types of peripheral neuropathies, all of which are fairly rare in dogs and cats. They may be degenerative, inflammatory, metabolic or vascular in nature. A number of situations and conditions can cause peripheral neuropathies including cancer, toxicity, injury or trauma.
The nervous system is divided into two main parts, the central nervous system and the peripheral nervous system. The central nervous system is made up of the spinal cord and the brain, while the peripheral nervous system includes the rest of the nerves in the body. A peripheral neuropathy causes loss of coordination, loss of reflexes, inability to feel pain and other complications.
A degenerative peripheral neuropathy occurs when the nerves gradually deteriorate. In most cases the cause of the deterioration is unclear. Acquired laryngeal paralysis is an example of a degenerative peripheral neuropathy that can affect large breed dogs.
Inflammatory peripheral neuropathies occur when the peripheral nerves or the connections between the nerves and the muscles become inflamed. This can lead to stiffness, tremors, weakness and paralysis. Both dogs and cats are susceptible to various forms of inflammatory peripheral neuropathy, including acquired myasthenia gravis and acute idiopathic polyradiculoneuritis.
Metabolic peripheral neuropathies are usually the result of an existing condition such as hypothyroidism or diabetes. They occur because of an imbalance in the hormones and sugars needed for normal nerve and muscle function. Vascular peripheral neuropathies occur due to an embolism that blocks blood flow to the limbs, causing partial paralysis.
Tumors, injury and trauma can all disrupt the normal function of the peripheral nervous system. Poisoning and tick-borne diseases can also cause serious problems. Several species of ticks may cause tick paralysis in both dogs and cats. After a tick bites an animal, partial paralysis of the hind legs occurs, worsening to full limb paralysis within 72 hours. The tick must be removed and medication given to reverse the paralysis. Even with treatment, some animals die of respiratory paralysis.