Glossary

Feline panleukopenia

A highly contagious and often deadly parvovirus that attacks fast-dividing cells, mainly in unvaccinated kittens.

Also called: feline distemper, cat distemper, FPV, feline parvovirus

Feline panleukopenia is caused by feline parvovirus. The name means a drop in all kinds of white blood cells, which the virus causes by attacking cells that divide fast, including those in the bone marrow and the lining of the gut. It is also called feline distemper, though it is unrelated to canine distemper.

Kittens that are unvaccinated or only partly vaccinated are at greatest risk. Signs include sudden lethargy, fever, refusing food, vomiting and diarrhea, and some cats hide near water bowls. In very young kittens the virus can damage the brain, and kittens infected before birth may be born with balance problems. Illness can progress within a day or two, so a sick kitten needs a vet quickly.

The virus is hardy and can survive in a home or shelter for a long time, and ordinary cleaners may not kill it. This is one reason shelters take outbreaks seriously and vets ask for a clean separation of sick animals. Vaccination is very effective and is one of the core vaccines given in the FVRCP combination. Ask your vet how to disinfect a space after an outbreak and when a new kitten can safely come home.

Last reviewed November 7, 2026

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Related terms

FVRCP vaccine The combination cat vaccine that protects against feline herpesvirus, calicivirus and panleukopenia. Core vaccines The vaccines vets recommend for every cat, as opposed to non-core vaccines chosen according to a cat's lifestyle and risk. Vaccine titer A blood test that measures antibodies to a germ, sometimes used to judge whether a cat is protected after vaccination. Upper respiratory infection A contagious infection of the nose, throat and eyes that causes sneezing, discharge and a poor appetite, common in kittens and shelter cats.

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