Younger dogs and puppies are the most susceptible to infection. The disease also strikes older dogs, although much less frequently. Cats are not susceptible to canine distemper. Infectious canine hepatitis is a separate disease but may occur simultaneously with canine distemper. Neither distemper nor infectious canine hepatitis is transmissible to man.
Canine distemper is a highly contagious disease caused by a tiny virus.
Canine distemper virus is most often transmitted through contact with mucous and watery secretions discharged from eyes and noses of infected dogs. Contact with the urine and fecal material of infected dogs can also result in infection. A healthy dog can be infected without coming in contact with an infected animal. Kennels, runs and other areas used by infected dogs can harbor canine distemper virus. The virus may be borne by air currents and inanimate objects.