Glossary
Canine distemper
A serious, vaccine-preventable virus that attacks a dog's respiratory, digestive and nervous systems, and spreads through the air.
Also called: CDV, distemper virus, hardpad disease
Canine distemper is caused by a virus that spreads by sneezing, coughing and contact with an infected dog's secretions. Wild animals such as raccoons and foxes can carry it too. Early signs resemble a bad cold, with fever, runny eyes and nose and cough, followed in some dogs by vomiting, diarrhea, and later seizures, twitching or paralysis. Some survivors have lasting nerve damage.
There is no drug that kills the virus, so a vet gives supportive care, and many dogs do not survive. Vaccination is the dependable defense, which is why distemper is part of the core vaccines and the DHPP combination shot.
Unvaccinated puppies, shelter dogs and dogs that meet wildlife are at higher risk. Call a vet at once if a puppy has these signs, and keep the dog away from others.
Last reviewed November 8, 2026