Coonhound paralysis (CHP) is a disorder of dogs that typically strikes one to two weeks after a dog is bitten by a raccoon. Symptoms of CHP generally begin with progressing partial or complete paralysis starting in the back legs and progressing to the front legs. Progression is variable: a dog may be completely paralyzed in as little as three days from the time symptoms first appear, or symptoms may worsen for up to ten days.
Coonhound paralysis and Guillain-Barre syndrome
Guillain-Barre syndrome, a rare disorder seen in humans, is very similar to CHP. This has resulted in researchers using CHP as an animal model for studying the human disease, but also applying what is known about Guillain-Barre to explain the syndrome in dogs.
Guillain-Barre syndrome typically follows a gastrointestinal or respiratory viral infection in humans (bacterial infections have been implicated as well), and is understood to be an autoimmune disease (an inappropriate immune reaction attacking the body’s own tissues) that affects the nerves. The myelin sheath of the nerve (illustration below) is damaged rendering the nerve less able to carry messages to and from the brain.
Is Coonhound paralysis caused by a virus?
Coonhound paralysis was initially thought to be a viral illness passed on by a raccoon bite and, as early as 1979, researchers succeeded in causing infection in a susceptible dog by inoculating it with raccoon saliva (Holmes et al.). However, some cases have occurred in dogs that have had no exposure to raccoons, suggesting that the explanation is more complicated.
The similarities to Guillain-Barre syndrome in humans provide an alternate explanation: CHP is likely a disease in which, following exposure to an infectious agent, the dog produces antibodies to its own nerve cells, damaging them and causing limb paralysis. There may be more than one infectious agent involved but at least one is carried and transmitted by raccoons.
Dogs susceptible to coonhound paralysis
Coonhound paralysis was initially seen in coonhounds, leading to the impression that this breed of dog is particularly susceptible to the disorder. It is likely, however, that coonhounds only appear to be more susceptible because they are more likely to be in contact with raccoons: very few dogs will suffer CHP after exposure to the virus or bacterium – of those that do, dogs that come into contact with raccoons will represent the majority.
An episode of CHP does not give the affected dog immunity against future episodes. In fact, it’s recommended that dogs that have had it be protected from subsequent exposure to raccoons. A second exposure is likely to set off a repeat onset of the syndrome.
Most dogs suffering from CHP can eat and drink, defecate and urinate. They also feel pain, even in the affected limbs. If the paralysis spreads to the respiratory muscles, more intensive care including mechanical respiration will be required if the dog is to recover. When given appropriate care and support, most dogs recover in weeks to months.
Sources
C.W. Dewey, “Disorders of the Peripheral Nervous System.” In: 50° Congresso Nazionale Multisala SCIVAC, 2005 – Rimini, Italia
Holmes, Dorothy F., Ronald D. Schultz, John F. Cummings, et al. “Experimental coonhound paralysis.” Neurology, 1979: 29
Medline Plus. “Guillain-Barre Syndrome” Accessed Sept 29, 2010.
Rosemary Drisdelle - Rosemary Drisdelle has been published many times as a nonfiction writer and several times as a poet. Her first book, Parasites: Tales of ...
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