Distemper is a name for several highly contagious viral diseases of animals, especially canine distemper. In dogs, it is caused by the canine distemper virus (CDV), a species of Morbillivirus causing distemper in dogs, wolves, foxes, raccoons, and ferrets. It is characterized by a fever, leukopenia, gastrointestinal and respiratory inflammation and sometimes, neurologic complications. In cats it is known as feline panleukopenia. While in some animals it may result in only mild infection, for example, in domestic cats, it causes severe disease in all canids (dog, wolf, fox), raccoons, pandas, and wild big cats.1 Many dogs with distemper die; animals that survive may suffer permanent neurological problems, such as convulsions and muscle twitching. Unvaccinated puppies are at most risk. In the 1960s, distemper was the number one infectious killer of dogs. Thanks to effective vaccinations, it is now quite rare.
The infection begins in the upper respiratory tract, then spreads from local lymph nodes to other lymphatic tissues and the gastrointestinal tract, and, in some cases, to the brain where it can persists due to its ability to evade its recognition by the immune system. The incubation period can range from 1 to 6 weeks, depending on the virus strain. The virus is discharged in the secretions of infected animals and is transmitted through respiratory droplets, urine, and saliva.2 A few days after exposure to the virus, the animal develops a fever, becomes lethargic, and refuses food and water. Further symptoms include coughing, discharge from the eyes and nose, and vomiting unrelated to eating and followed by bloody diarrhea. At this stage, severely affected dogs and puppies can die suddenly, but supportive therapy can decrease the risk. Recovered dogs frequently show persistent nervous tics or involuntary movements of one or more legs. In some cases, a hyperkeratosis (hard pad) develops on the foot pads. Most recovered dogs clear the virus completely, although some may harbor it in their central nervous system. Dogs that do not receive periodic immunizations can lose their protection and become infected after stress, immunosuppression, or contact with a diseased animal.
- Brian W.J.Mahy, Marc H.V. van Regenmortel. Desk Encyclopedia of Animal and Bacterial Virology.
- C. Greene. Infectious Diseases Of The Dog And Cat.