Canine distemper is a viral respiratory disease that can progress to cause brain damage. Fortunately, many pets infected with distemper do not become seriously ill, but when they do become ill, about half will die. Puppies or older dogs with weak immune systems usually die from distemper.
The distemper virus is similar to the human measles virus. The virus is successful because it suppresses the immune system and actually multiples within the immune system as it spreads throughout the body.
Distemper is highly contagious and spreads as dogs breathe or cough on each other (aerosol infection). It also spreads through discharge from the eyes and nose, and even from food and water that has been contaminated. Fortunately, cleaning with household detergents can easily kill the virus. This is unlike parvovirus that persists in the environment unless killed with bleach or strong chemicals.
Puppies and older dogs with poor immune function are prone to develop distemper infections. This disease also infects many wild animals including hyenas, mink, weasels, and raccoons, so extra precaution is needed for outdoor pets or pets living in rural areas. Distemper occurs throughout North America, Europe, and Australia and is one of the leading causes of death in dogs.
Occasionally, humans are infected with the distemper virus, but it does not cause symptoms. Scientists investigated humans with canine distemper virus to see if there was a connection between distemper and the development of multiple sclerosis (MS), but they did not find one.