Glossary
Canine parvovirus
A highly contagious, often deadly virus that attacks the gut and bone marrow, mainly in unvaccinated puppies, and is preventable by vaccination.
Also called: parvo, CPV, parvo virus, parvovirus type 2
Canine parvovirus, or parvo, is a hardy virus passed through feces and contaminated ground, shoes and surfaces. It can survive in the environment for months. It damages the intestinal lining and the immune system, causing vomiting, severe and often bloody diarrhea, loss of appetite, lethargy and dehydration.
Puppies between about six weeks and six months old, and dogs that are unvaccinated or only partly vaccinated, are most at risk. Puppies are not fully protected until they finish their vaccine series, so many vets advise keeping them away from places where unvaccinated dogs have been.
Parvo is an emergency. Fast hospital care with fluids greatly improves survival, so call a vet immediately if a puppy has vomiting and diarrhea. Parvo is a dog virus and is not the same as the human parvovirus.
Last reviewed November 8, 2026