Introduction

Coonhound paralysis, actually called idiopathic acute polyradiculoneuritis, is an acute inflammatory condition of nerves and nerve roots. The popular name persists because early cases of the condition were thought to be caused by contact with raccoon saliva. Hunting dogs occasionally developed this disorder roughly one week after being bitten by a raccoon. However, many cases of Coonhound paralysis occur spontaneously in dogs with no exposure to raccoons. Whatever the underlying cause, Coonhound paralysis is thought to involve an immune-mediated attack on peripheral nerves and nerve roots located near the base of the spinal cord, causing paralysis that can range from mild to very severe. Clinical signs of this disorder develop rapidly and often start with hind end weakness of unknown origin.

Symptoms of Coonhound Paralysis

Coonhound paralysis can occur in dogs of any breed, age or gender, but it seems to show up more frequently in outdoor dogs and hunting dogs after contact with a raccoon. Symptoms develop quickly and typically include many or most of the following:

• Progressive hind end weakness of unknown origin that worsens over 5 to 10 days
• Changes in vocalization (bark becomes raspy and hoarse due to vocal cord damage)
• Stiff, stilted gait; progresses to affect all limbs
• Loss of leg reflexes
• Loss of muscle tone
• Severe muscle wasting (atrophy)
• Rapid progression to complete flaccid paralysis in all four legs
• Hypersensitivity to touch (hyperesthesia); vigorous objection even to very light contact or mild stimulation
• Sensory function remains intact in almost all dogs, including the sensation of pain

One of the most confusing aspects of this condition for owners is that most affected dogs continue to urinate and defecate normally and can still wag their tails. Most also can chew and swallow normally and do not have pupillary or other eye abnormalities. In a very few cases, the facial nerves become damaged, although appetite and thirst almost always are unaffected. The paralysis generally worsens for several days once clinical signs appear, and then stabilizes. Most dogs will develop relatively few symptoms other than limb paralysis and will eventually recover spontaneously, without treatment and without permanent neurological damage. Unfortunately, respiratory paralysis occasionally occurs, and some dogs become severely debilitated. In those cases, hospitalization with mechanical respiratory support may be essential to the dog’s survival.

Dogs at Increased Risk

“Coonhound” is a term loosely applied to a number of different hunting dogs, most of which live in the southern United States. Few of these are recognized as specific breeds by any official canine organization. Outdoor dogs allowed to roam freely and hunting dogs in areas frequented by raccoons are at an increased risk of developing Coonhound paralysis, although it can occur in other dogs as well, for no apparent or identifiable reason.