Canine parvovirus
Also called Parvo, parvoviral enteritis
A highly contagious viral gut disease of young, unvaccinated dogs. It causes vomiting, severe and often bloody diarrhoea and dehydration, and can be fatal without early treatment.
Cause and spread
- Cause
- Canine parvovirus (CPV), a hardy virus that attacks the lining of the gut, the bone marrow and, in very young puppies, the heart.
- How it spreads
- By contact with infected dogs or their faeces. Dogs shed the virus before they look sick and for about 10 days after recovery, and the virus survives in the environment for months or longer.
Signs to watch for
- Loss of appetite and lethargy
- Vomiting
- Diarrhoea, often bloody and foul-smelling
- Fever and dehydration
- Weakness and collapse
- Sudden heart failure in very young puppies
Many diseases look alike. Only a laboratory test can tell them apart, so please see a veterinarian for any sick animal.
How it is diagnosed
Diagnosis is based on history, examination and a test on a faecal sample. PCR finds the virus's genes in faeces or a rectal swab. A blood count often shows a low white cell count, and checking for worms matters because other infections make parvo worse.
- Usually the first testCanine Parvovirus PCRDetects the virus in faeces or a rectal swab.
- Usually the first testPuppy Parvo and Distemper Panel (panel)Parvovirus and distemper tested together.
- Supports the diagnosisComplete Blood Count (CBC)Shows a drop in white blood cells and how sick the puppy is.
- Supports the diagnosisFaecal FlotationFinds worms that make the illness worse.
Prevention and control
- Vaccinate puppies at 6 to 8, 10 to 12 and 14 to 16 weeks of age, as advised by your veterinarian
- Keep unvaccinated puppies away from other dogs and public places
- Disinfect bedding, bowls and toys; the virus resists many disinfectants
- Deworm puppies and control other gut parasites
Where this information comes from
- Canine Parvovirus Infection (Parvoviral Enteritis in Dogs) · Merck Veterinary Manual
General information for animal owners and veterinarians, last checked October 2026. It does not replace the advice of your veterinarian, who should decide which tests and treatment your animal needs.