Feline leukemia spreads through saliva, blood, and urine—mostly between cats that live together or fight

Feline leukemia virus (FeLV) passes from one cat to another primarily through saliva. A cat can transmit the virus by grooming another cat, sharing food or water bowls, or biting during a fight. Blood and urine also carry the virus, though saliva is the most common route. Kittens can contract it from their mother during pregnancy or nursing. The virus does not survive long outside the body—usually only a few hours on surfaces—so casual contact with contaminated objects is a low-risk transmission route.

Outdoor cats and cats in multi-cat households face the highest risk because they have more direct contact with other cats. Indoor cats living alone have almost no risk of contracting FeLV unless they are exposed to an infected cat or contaminated materials brought into the home.

Key Takeaways

  • Saliva is the primary transmission route, spreading through grooming, shared food bowls, and bites.
  • Kittens born to infected mothers can contract the virus during pregnancy or while nursing.
  • The virus dies quickly outside the body, so environmental transmission is uncommon.
  • Outdoor cats and cats in multi-cat households have significantly higher exposure risk than indoor-only cats.
  • A single infected cat in a household can transmit the virus to other cats over weeks or months of close contact.

Saliva as the main transmission route

Saliva carries the highest concentration of feline leukemia virus and is responsible for most infections. When an infected cat grooms another cat, shares a food or water bowl, or bites during play or fighting, virus particles in saliva enter the other cat's mouth or through small cuts in the skin. Even a cat that appears healthy can shed virus in saliva for weeks or months before showing any symptoms.

Shared litter boxes also pose a transmission risk because cats may have small cuts or sores in their mouth or digestive tract. If an infected cat uses the box and then another cat uses it shortly after, the virus can potentially enter through these small wounds. This is why multi-cat households are considered higher-risk environments.

Blood and urine transmission

Blood carries feline leukemia virus and can transmit infection if it enters another cat's bloodstream through a bite wound or cut. Cats that fight outdoors or play roughly indoors may exchange blood during these encounters. Urine also contains the virus, though transmission through urine alone is less common than through saliva or blood.

Veterinary needles or surgical instruments that contact infected blood can theoretically transmit the virus if not properly sterilized, though modern veterinary practices use standard infection control to prevent this. Sharing grooming tools or nail clippers between cats is not considered a significant transmission risk because the virus does not survive long on these surfaces.

Mother-to-kitten transmission

A pregnant cat infected with feline leukemia can pass the virus to her kittens during pregnancy through the placenta or during nursing through her milk. Kittens born to infected mothers have a high likelihood of contracting the virus, and many will show symptoms within weeks or months. Some kittens may be born already infected, while others may contract it after birth through nursing.

This is one reason why testing pregnant cats or cats of unknown status before breeding is important. Kittens nursing from an infected mother should be tested at 8 weeks of age and again at 12 weeks, as antibodies from the mother can initially mask the presence of the virus.

Why the virus does not spread through the environment

Feline leukemia virus is fragile outside the cat's body. It breaks down within a few hours when exposed to air, heat, or cleaning products. This means the virus does not survive on food bowls, litter boxes, toys, or bedding long enough to infect another cat unless that cat contacts the contaminated item within a very short window.

Standard household cleaning with soap and water, or any disinfectant, destroys the virus. This is why a cat that recovers from FeLV (or a new cat introduced to a home where an infected cat lived) does not face ongoing environmental risk. The home itself does not need special decontamination—regular cleaning is sufficient.

Risk factors that increase transmission

Outdoor cats have the highest risk of exposure because they encounter other cats, fight, and share resources like water sources and shelter. Cats in shelters or rescue facilities also face elevated risk due to the number of cats in close quarters. Multi-cat households where cats share litter boxes, food bowls, and sleeping areas create conditions for the virus to spread slowly from one cat to another over time.

Young kittens and elderly cats are more vulnerable to infection once exposed because their immune systems are weaker. Cats with other illnesses or stress may also be more susceptible. A single infected cat introduced to a household of uninfected cats can transmit the virus to some or all of them, depending on how much direct contact occurs and how long the infected cat remains in the home.

Testing and prevention in multi-cat homes

If you have multiple cats or are introducing a new cat to your home, testing before or shortly after introduction can prevent transmission. A blood test detects feline leukemia virus and should be done at the time of introduction and again 4 to 6 weeks later, since the virus takes time to show up in blood tests after infection. Keeping a newly infected cat separated from other cats can slow or prevent spread to the rest of the household.

Vaccination is available for cats at risk of exposure, though it is not 100 percent effective. Vaccination is typically recommended for outdoor cats, cats in multi-cat households, or cats with unknown exposure history. Indoor cats with no contact to other cats do not usually need vaccination unless they may be exposed in the future.

Frequently Asked Questions

Can a cat get feline leukemia from a single exposure?

A single exposure can transmit the virus, but infection is not may provide. The amount of virus present, the route of exposure, and the exposed cat's immune system all affect whether infection occurs. Repeated or prolonged contact with an infected cat increases the likelihood of transmission.

Is feline leukemia contagious to humans or other animals?

No. Feline leukemia virus infects only cats and some other felines like lions and tigers. It cannot infect humans, dogs, or other household pets. You cannot contract the virus from handling an infected cat or cleaning up after it.

How long can an infected cat shed the virus?

Some cats shed the virus for their entire lives, while others may stop shedding after a few months. A cat can transmit the virus to other cats for weeks or months before showing any symptoms itself, which is why testing is important in multi-cat households.

Can feline leukemia spread through scratches?

Scratches alone are not an efficient transmission route unless they break the skin and allow saliva or blood to enter. Bites are much more likely to transmit the virus because they create deeper wounds and involve direct contact with saliva.

What should I do if my cat was exposed to a cat with feline leukemia?

Contact your veterinarian. They can test your cat immediately and again 4 to 6 weeks later to determine if infection occurred. In the meantime, keep your cat separated from other cats in your household to prevent potential spread if infection develops.