Updated September 25, 2026. Fact-checked against veterinary sources; review by a licensed veterinarian is in progress. See our editorial policy.
Quick answer: Feline leukemia virus (FeLV) is a contagious virus that spreads between cats mainly through saliva: mutual grooming, shared bowls, and bites. It can also pass from mother to kittens. Some infected cats clear the virus or keep it in check, while others develop a lifelong progressive infection that can cause anemia, lymphoma, and a weakened immune system. There’s no cure, but many FeLV-positive cats live good lives for years with good care. Testing and vaccination are the best protection.
How FeLV spreads
- Close, friendly contact: grooming, sharing food and water bowls or litter boxes
- Bite wounds
- From an infected mother to kittens during pregnancy or nursing
FeLV doesn’t survive long in the environment and isn’t a risk to people, dogs, or other species.
Possible outcomes of infection
- Abortive: the cat’s immune system clears the virus.
- Regressive: the immune system controls the virus, but viral genetic material stays in the cat’s cells. These cats usually stay healthy but can reactivate the infection under stress or illness.
- Progressive: the virus isn’t contained. These cats are more likely to develop FeLV-related diseases and shed virus to other cats.
Diseases linked to FeLV
- Anemia and other blood cell problems
- Lymphoma and leukemia
- Weakened immunity, leading to repeated infections
- Mouth inflammation (stomatitis)
- Reproductive problems
Testing
- Screening test at the clinic (antigen test): detects virus in the blood.
- PCR test: detects viral genetic material and helps clarify unclear results or regressive infections.
- Retest positives and recent exposures: a cat exposed recently may need retesting after about 30 days or more, since early results can be negative.
- Test all new cats before introducing them to your household, and test sick cats, cats with bite wounds, and before FeLV vaccination.
Prevention
- Vaccination: feline vaccination guidelines recommend the FeLV vaccine for all kittens, with boosters for adult cats that go outdoors or live with FeLV-positive cats.
- Indoor living greatly reduces exposure.
- Test new cats before they share space with your other cats.
Caring for an FeLV-positive cat
- Keep your cat indoors to protect other cats and reduce its exposure to infections.
- Vet checkups at least every 6 months, with bloodwork, to catch problems early.
- Complete, cooked diet: avoid raw food and raw milk, which carry infection risk.
- Keep up with other vaccines and parasite control as your vet advises.
- Prompt vet care for any illness, since infections can progress faster.
- Housing with other cats: ideally, positive cats live only with other positive cats. If they must share space with negative cats, the negative cats should be vaccinated, though vaccination isn’t 100% protective.
Treatment
There’s no cure. Treatment focuses on the diseases FeLV causes, such as antibiotics for infections, treatment for anemia, and chemotherapy for lymphoma. Some antiviral and immune-modulating drugs are used, but evidence for them is limited.
What to avoid
- Unproven “cures” or supplements claiming to eliminate the virus.
- Letting a positive cat roam outdoors.
- Euthanizing a healthy cat based on a single test: confirm the result and discuss the outlook with your vet.
Frequently asked questions
How long do FeLV-positive cats live?
Cats with progressive infection often live around 2–3 years after diagnosis, on average, but many live longer with good care. Cats with regressive infection may live normal lifespans.
Can people catch FeLV?
No. FeLV only infects cats.
Is FeLV the same as FIV?
No. They are different viruses. FIV spreads mainly through deep bite wounds and has no widely available vaccine in the US.
Sources
- Little SE, et al. 2020 AAFP Feline Retrovirus Testing and Management Guidelines. J Feline Med Surg. 2020
- Stone AE, et al. 2020 AAHA/AAFP Feline Vaccination Guidelines. J Feline Med Surg. 2020
- Levy JK, et al. Long-term outcome of cats with natural FeLV and FIV infection. 2006
- Cornell Feline Health Center: Feline leukemia virus
- Merck Veterinary Manual: Feline leukemia virus
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.