Feline leukemia is highly contagious between cats, but not to humans or other animals

Feline leukemia virus (FeLV) spreads easily from one cat to another through saliva, blood, urine, and feces. An infected cat can pass the virus to a healthy cat by grooming, sharing food bowls, or fighting. The virus does not survive long outside the body—usually only a few hours on surfaces—so transmission requires direct contact or contact with fresh bodily fluids. Humans cannot catch feline leukemia, and neither can dogs or other non-feline animals.

Not every cat exposed to FeLV becomes infected. A cat's age, immune system strength, and the viral load it encounters all affect whether infection takes hold. Kittens and very old cats are more likely to develop persistent infection than healthy adult cats, who sometimes clear the virus on their own within weeks.

Key Takeaways

  • Feline leukemia spreads through saliva, blood, urine, and feces, making it highly contagious between cats living in the same household.
  • The virus dies quickly outside the body, so transmission requires direct contact or contact with fresh bodily fluids rather than contaminated surfaces.
  • Kittens and elderly cats are at highest risk of developing persistent infection after exposure.
  • Vaccinating uninfected cats and keeping infected cats separated from uninfected ones are the main ways to prevent spread.
  • Humans, dogs, and other non-feline animals cannot catch feline leukemia.

How the virus moves from cat to cat

The most common route of transmission is through saliva. When an infected cat grooms another cat, shares a water bowl, or engages in mutual grooming with a healthy cat, the virus can enter through the mouth or nose. Fighting and bite wounds create an even more direct path, as the virus in blood and saliva enters through broken skin.

Urine and feces also carry the virus. A cat using a litter box after an infected cat, or grooming itself after contact with contaminated urine or feces, can become infected. This is why multi-cat households with shared litter boxes face higher transmission risk. Mothers can also pass the virus to kittens before or shortly after birth, though this is less common than direct contact transmission.

The virus is fragile outside the body. It typically survives only a few hours on food bowls, litter box surfaces, or bedding, especially if those surfaces dry out. This means that thorough cleaning of shared items and separate litter boxes can reduce—though not eliminate—transmission risk in a household with both infected and uninfected cats.

Why some cats get infected and others don't

Exposure to FeLV does not automatically mean infection. A cat's immune system can sometimes fight off the virus before it establishes itself. Healthy adult cats exposed to FeLV clear the infection on their own in roughly 30 to 40 percent of cases, particularly if the viral exposure is low. These cats develop immunity and cannot be reinfected.

Age is the strongest predictor of outcome. Kittens under 8 weeks old almost always develop persistent infection if exposed. Cats between 8 weeks and 1 year old have a moderate risk—roughly 50 to 90 percent develop persistent infection depending on the strain and exposure level. Adult cats over 1 year old are more likely to clear the virus, though many still develop persistent infection.

Individual immune system strength also matters. Cats with other illnesses, poor nutrition, or chronic stress are more vulnerable to persistent infection than healthy cats. A cat's genetics may also play a role, though this is not yet fully understood.

The difference between exposure and persistent infection

Exposure to FeLV and persistent infection are not the same thing. A cat can be exposed to the virus and either clear it within weeks or develop a persistent infection that lasts for life. A persistently infected cat sheds virus continuously and poses an ongoing transmission risk to other cats. A cat that cleared the virus is no longer contagious.

The only way to know whether a cat has persistent infection is through blood testing. A veterinarian can perform an ELISA test (enzyme-linked immunosorbent assay) or an IFA test (immunofluorescence assay) to detect the virus. Some cats test positive immediately after infection; others may not test positive for weeks. A cat that tests negative may still be in the window period before the virus becomes detectable, so retesting after 8 to 12 weeks is sometimes recommended if exposure is suspected.

Preventing transmission in multi-cat households

The most effective prevention is vaccination. The FeLV vaccine is given as a series of shots starting at 8 weeks of age, with boosters at 12 weeks and 1 year, then every 1 to 3 years depending on the vaccine and the cat's risk level. Vaccinated cats have strong protection against infection, though breakthrough infections can occur in rare cases. Vaccination does not work once a cat is already persistently infected.

If a cat tests positive for FeLV, the standard recommendation is to keep it separated from unvaccinated or untested cats. This means separate litter boxes, food bowls, and ideally separate rooms. If separation is not possible, frequent handwashing between handling infected and uninfected cats, and disinfecting shared surfaces with bleach solution (1 part bleach to 10 parts water), can reduce risk.

Testing all cats in a household when one tests positive helps identify which cats are infected and which are not. Cats that test negative should be vaccinated and kept separate from the infected cat. Some owners choose to house all cats together and accept the risk of transmission; others prioritize separation. A veterinarian can discuss the options based on the household's specific situation.

What happens after a cat is infected

A cat with persistent FeLV infection can live for months or years, though the average lifespan after diagnosis is 2 to 3 years. The virus weakens the immune system over time, making the cat vulnerable to secondary infections like bacterial infections, fungal infections, and certain cancers. Some infected cats develop anemia, kidney disease, or neurological problems.

An infected cat may show no symptoms for months or years—this is called the latent phase. During this time, the cat still sheds virus and can transmit it to other cats. Once symptoms appear, they often include poor appetite, weight loss, lethargy, fever, diarrhea, or respiratory infections. The progression and severity vary widely between individual cats.

There is no cure for persistent FeLV infection. Treatment focuses on managing symptoms and secondary infections, keeping the cat comfortable, and monitoring for complications. Regular veterinary checkups, good nutrition, and a low-stress environment can help maintain quality of life.

Frequently Asked Questions

Can I catch feline leukemia from my cat?

No. Feline leukemia virus infects only cats and some other felines like lions and tigers. Humans cannot catch it. You can handle, pet, and live with an infected cat without risk to yourself, though you should wash your hands after handling to avoid spreading the virus to other cats.

If my cat was exposed but tests negative, is it safe?

A negative test usually means the cat either cleared the virus or was not infected. However, if exposure was very recent, the virus may not yet be detectable. A veterinarian may recommend retesting after 8 to 12 weeks if exposure is suspected and the cat remains at risk.

Can an indoor cat catch feline leukemia?

Indoor cats are at much lower risk than outdoor cats, but transmission is still possible if an infected cat is brought into the home or if the cat has contact with infected cats through windows or doors. Vaccination is recommended for all cats, even indoor ones, depending on their risk level and local prevalence.

How long does the virus survive on my hands or clothes?

FeLV survives only a few hours on skin, clothing, or other surfaces. Washing your hands with soap and water after handling an infected cat is sufficient to remove the virus. The main transmission risk is direct contact between cats, not contact with contaminated objects or clothing.

Should I test my cat if another cat in my home has FeLV?

Yes. Testing all cats in the household helps identify which ones are infected and which are not. Uninfected cats can then be vaccinated and kept separate from the infected cat if desired. Your veterinarian can recommend a testing schedule based on your household's situation.