Canine distemper is a highly contagious disease of wild and domestic carnivores. Distemper is caused by a virus that has a broad host range among North American carnivores including the gray fox, raccoons, coyotes, skunks, and weasels. Canine distemper virus is related to rubeola (red measles) but poses no known threat to humans.
Distemper occurs most often in raccoons throughout the Southeastern U.S. and is cyclic in nature, tending to show up approximately every five to seven years. It may appear as sporadic isolated cases or in widespread outbreaks. In wild animals, the juveniles are more susceptible to the infection; therefore, the majority of cases are seen in the spring and summer when juvenile populations are at their highest levels. However, distemper outbreaks may occur year round.
A healthy animal may contract canine distemper from direct contact with an infected animal or its bodily secretions and waste. Under most environmental conditions the virus does not survive long outside the body; therefore, transmission requires close interaction between animals to enable direct contact or aerosol exposure.
Infected animals may shed the virus starting approximately five days after infection, for a period of as long as six weeks or until death.
Unvaccinated dogs and cats are susceptible to contracting the disease. Pet owners are reminded to keep their pet vaccinations up to date.
Many of the symptoms displayed by an animal with distemper are very similar to symptoms displayed by a rabid animal (only testing of brain tissue can determine if an animal is rabid). Although distemper poses no threat to humans, any one bitten or scratched by a raccoon must contact their physician immediately. Exposure to a rabies vector species (raccoons, coyotes and foxes) may be fatal. Rabies has been documented in east Tennessee and an aggressive oral vaccination program has been initiated.
Symptoms of the disease are similar in all susceptible species. The symptoms include distress, coughing, sneezing, diarrhea, discharge from eyes and/or nostrils, eyelids that are crusted over and stuck together, and hardened footpads.
Infected animals may have convulsions, tremors and chewing fits. These animals may lose their fear of humans, become aggressive, appear blind, stumble and fall. Infected animals may exhibit stupor, paralysis, coma, and convulsions. An infected animal that is typically nocturnal may be observed in the daylight wandering aimlessly.
Definitive diagnosis is based on laboratory analysis of affected tissues by fluorescent antibody techniques.
Canine distemper runs its course rapidly. Distemper is often fatal and death is usually attributed to a secondary infection such as pneumonia. Not all raccoons get the disease and many survive the outbreaks.
No specific drug is available that will kill the virus in infected animals. An animal that is symptomatic can not be treated; therefore, infected animals should not be handled by the public.
Other diseases which may mimic distemper include rabies, tularemia, histoplasmosis (raccoons) and poisonings. Raccoon rabies was first documented in east Tennessee in 1993,
In Tennessee, die-offs of raccoons due to canine distemper occur regularly. Outbreaks of canine distemper may have a significant impact on local or regional populations of raccoons, gray foxes and skunks in parts of the United States. The transmission of canine distemper is likely density-dependent; the disease poses a threat mainly to concentrated populations of previously unexposed susceptible species.
Canine distemper is of no public health significance to humans.