Polyneuropathy in Dogs

Polyneuropathy, meaning many abnormalities of the nervous system, is marked by clinical signs that include progressive weakness in the limbs, exercise intolerance, high-steppage, change in bark pitch and difficulty breathing. Sometimes called chronic relapsing polyneuropathy, the disorder is caused by damage to the fatty covering that encircles and protects nerve fibers. 

Neuropathy means a disease of, or damage to nerves. When it occurs outside of the brain or spinal cord, it is called a peripheral neuropathy. When particularized to dogs and cats, polyneuropathy is a collection of peripheral nerve disorders that are often breed-specific. Unlike mononeuropathy in which one nerve type is affected, polyneuropathy stipulates the involvement of three types of peripheral nerves -- sensory nerves, motor nerves, and autonomic nerves. Overall, any nerve damage interferes with the function of these peripheral nerves.  

It’s no wonder that canines with peripheral neuropathy often struggle to maintain balance, respiration, and other vital functions. Polyneuropathy in dogs often strikes without warning anywhere from ten to twenty months of age. Opposite to acute neuropathy, symptoms of chronic neuropathy begin slowly and increase over time.

Canine polyneuropathy is a neurological disease characterized by a dysfunction of peripheral nerves.

Symptoms may be varied and inconsistent.

• Change in gait
• Loss of bark
• Weakness in legs
• Tremor
• Lack of coordination
• Resistance to standing and walking
• Difficulty swallowing
• Atrophy
• Loss of pain sensation leading to self-mutilation

Types

Two examples of peripheral neuropathies include Dancing Doberman disease and an idiopathic polyneuropathy associated with the Alaskan Malamute. Alaskan Malamutes are known to inherit diseases that progressively enervate their instinctual desire to hunt and work. Alaskan Malamute Polyneuropathy (AMPN) causes atrophy of the spinal muscle, a noticeable change in gait, as well as symmetric hind limb weakness. Significant changes may include an inability to walk up the stairs or jump.  While some partially recover, many Malamutes are euthanized due to a markedly decreased quality of life.  Dancing Doberman Disease (DDD) is another example of a breed-related, progressive peripheral neuropathy. This problem is relatively rare and only affects Doberman Pinschers. Soon after onset, the Doberman may begin to resist putting weight on both hind legs. A continual shifting behavior explains the dancing term. There appears to be no pain, but muscles in the unused legs may eventually lose sensation. Even with the progression toward muscle atrophy, dogs with DDD often live long, healthy lives.

The job of the peripheral nervous system (PNS), is to carry information from the central nervous system, the brain, and spinal cord, to the rest of the body. While sensory nerves relay messages about touch, smell and taste, motor nerves serve to help the brain control the muscles. Autonomic nerves are central to the body as they control heart rate, breathing and digestion. Nerve damage substantially impacts the communication between the PNS and the entire body.

Diagnosis of peripheral neuropathy is difficult, and often requires a neurological examination, diagnostic tests such as ultrasound and chest x-rays, a muscle biopsy and electronic testing of nerve response and activity. Your veterinarian, or a veterinary neurologist, may also recommend blood testing and a spinal tap to check for various disorders. It will be important to test for conditions that may present in a similar manner such as a tumor or other neurological disease, in order to rule them out.

Currently, there is no treatment for these conditions. Though top researchers and veterinary colleges have devoted decades to the study of canine polyneuropathy, there are still more questions than answers. Symptoms vary considerably from dog to dog, and in most cases, the onset of symptoms is sudden rather than progressive. While some dogs appear to grow out of it, others decline so sharply that they require euthanasia.

Since the extent and nature of the disease varies so greatly from dog to dog, it is difficult to predict chances for recovery. Though your dog may suddenly appear to improve, he may present with new symptoms within a short period. No matter the course of the disease, your canine will never fully return to the state or condition pre-onset. Thus, it’s recommended to continually monitor symptoms and evaluate your pet’s quality of life.

It is also important to remove any affected dog from a breeding environment. Neutering your dog is advisable not only to prevent breeding, but also to lessen undue stress.