My dog suddenly became weak and subsequently wasn't able to walk. The veterinarian suspects coonhound paralysis. We are awaiting some test results. What is coonhound paralysis? Is my dog likely to get better?
Coonhound paralysis, or polyradiculoneuritis, is an inflammatory condition of several spinal nerve roots and peripheral nerves that affects dogs. It closely resembles Guillain-Barreó syndrome in humans. Affected dogs develop signs of motor nerve disease, which may include respiratory paralysis and weakness or flaccid paralysis of the limbs. The various breeds of dogs functionally grouped as coonhounds seem to be at higher risk of acquiring it. However, any dog regardless of breed may develop this disease. Polyradiculoneuritis is not a common ailment of dogs.
There are two basic types of polyradiculoneuritis. One type arises in some dogs after exposure to raccoons. The other type is not known to be associated with any such vector exposure. Both types present essentially identical signs of disease. Genetic mechanisms are not presently believed to be a causal factor. Many veterinarians believe the relatively higher occurrence of this disease in coonhounds is due to their higher frequency of exposure to raccoons. Although polyradiculoneuritis is thought to be an immune-mediated process, the underlying trigger event is not known and is presently hypothetical. Re-activation of a previous infection with a respiratory or gastrointestinal virus, bacterium or parasite, whether acquired naturally or through a vaccine, has been postulated as an underlying mechanism.
In addition to weakness or paralysis of limbs and respiration, an affected dog may have difficulty barking or may even lose its voice. It may develop heightened sensitivity along its back. Generally, affected dogs will retain their ability to sense pain and to control eating and eliminative functions.
Diagnosis is based on clinical history, findings at physical and neurological examination and on the basis of certain tests. Analysis of cerebrospinal fluid samples obtained at different levels of the spinal cord can reveal a characteristic composition, but this is inconsistent. Nerve conduction and electromyography tests will document patterns of motor nerve weakness or paralysis and muscle dysfunction. (These tests are only available at a limited number of veterinary referral centers, however.) Blood tests may show elevated levels of certain immune system proteins. In cases with flaccid paralysis, neurologists will rule out botulism and tick paralysis before a diagnosis of polyradiculoneuritis is made.
Treatment is supportive. Affected dogs are given respiratory support as needed and nursing care. Since the underlying cause is not known, no specific medications may be rationally given. Corticosteroid drugs, which are frequently given to treat other diseases with a suspected immune-mediated cause, are specifically not given to dogs affected with this disease. (When people affected with Guillain-Barre
ó syndrome are given steroids they get worse.) Polyradiculoneuritis typically runs its course over several weeks to several months; a three-month course is typical. Most dogs recover; some may retain mild signs of the disease. However, no immunity is imparted to recovered dogs, and recurrent episodes of the disease may arise.
01/04/01
