The virus does not survive easily in the environment and it is killed by most disinfectants.
The virus is transmitted from animal to animal by aerosol.
Canine distemper virus affects three main organ systems causing signs of disease :
The disease has an incubation period of about 7 days, and the first sign might be malaise, depression and a high body temperature. Animals may appear to recover in 2-4 weeks but in some recovered dogs persistent infection can lead to "old dog encephalitis" in later life.
Many dogs have circulating antibodies to canine distemper due to vaccination or natural exposure to the virus, so serological tests are unreliable as a form of diagnostic test.
If bitches are fully vaccinated they will pass on passive immunity to their puppies through the first milk (colostrum) and this protection falls off after 8 weeks, so the puppies should be vaccinated from that time. Measles vaccine can be used to give cross-protection to distemper, and this is given to provide some immunity to young puppies (from about 6 weeks to 12 weeks of age) that have been exposed to the disease even though maternal antibodies may be present.
All dogs should be protected by vaccination, and modified live vaccines are widely available. Two vaccines are given at the puppy stage and immunity can last for as long as 7 years in some individuals. However, it is usual to recommend booster vaccines - at 1-3 year intervals.
Vaccinated dogs can still become infected by canine distemper virus but they only show mild or no signs.
Once severe central nervous signs occur euthanasia is usually recommended.
Long term problems
"Old dog encephalitis"