Felv in Cats

Feline leukemia virus, usually called FeLV, is one of the most important infectious diseases in cats. It spreads mainly through close contact with infected cats, especially saliva, nasal secretions, bite wounds, grooming, and from mother cats to kittens. FeLV does not infect people or dogs, but it can have major effects on a cat’s health because it can weaken the immune system, damage bone marrow, and raise the risk of certain cancers, especially lymphoma.

Some cats clear or control the infection after exposure, while others develop persistent infection. That difference matters because persistently infected cats are more likely to shed virus and become sick over time. A cat may look healthy for months or even years after testing positive, so a positive result does not always mean immediate illness. Still, FeLV-positive cats need an ongoing care plan with your vet because problems such as anemia, mouth inflammation, chronic infections, weight loss, and cancer can develop later.

In the United States, FeLV infection is less common than it once was because of testing and vaccination, but it still matters. Cornell notes that about 2% to 3% of all cats in the U.S. are infected, with much higher rates in sick or high-risk cats. That is why testing new cats before they join a household is so important, especially if other cats are present.

For pet parents, the key point is that FeLV is manageable even though it is not curable. The goal is not one single treatment. Instead, your vet may recommend a spectrum of care that can range from regular monitoring and indoor management to more advanced diagnostics, hospitalization, transfusions, or cancer care depending on your cat’s symptoms and your goals.

Diagnosis usually starts with a screening blood test done in your vet’s office. The most common first test detects FeLV antigen in the blood. This is often used when a cat is newly adopted, before FeLV vaccination, after a bite wound or known exposure, or when a cat is sick. A positive screening result does not always tell the whole story, because some cats have transient infection and others have persistent infection. Your vet may recommend repeat testing in about 30 days or additional confirmatory testing depending on the result and your cat’s risk.

If a cat tests positive, your vet may also suggest baseline lab work such as a complete blood count, chemistry panel, and urinalysis. These tests do not diagnose FeLV by themselves, but they help show whether the virus has already affected red blood cells, white blood cells, kidneys, liver, or hydration status. If your cat has enlarged lymph nodes, masses, chronic mouth disease, or other concerning signs, your vet may recommend imaging, needle aspirates, biopsy, or other tests to look for lymphoma, secondary infection, or organ involvement.

Testing strategy matters in multi-cat homes. New cats should be tested before introduction, and exposed housemates may need testing and vaccination planning. Even healthy FeLV-positive cats benefit from periodic rechecks because early changes in blood counts or weight can guide care before a crisis develops.

FeLV is caused by infection with feline leukemia virus, a retrovirus that infects cats. The virus is shed most heavily in saliva and nasal secretions, but it can also be present in urine, feces, blood, and milk. Spread usually happens through prolonged close contact, mutual grooming, shared bowls, bite wounds, and from an infected mother cat to kittens before or after birth. The virus does not survive long outside the body, so routine household surfaces are less important than direct cat-to-cat exposure.

Risk is highest in kittens, young cats, outdoor cats, cats that fight, and cats living with FeLV-positive housemates. Sick cats and cats from crowded or unknown-background environments may also be at higher risk. Age matters because adult cats are generally more resistant than kittens, but adults can still become infected, especially after repeated exposure or bite wounds.

A positive FeLV test is not a sign that a pet parent did something wrong. Many infected cats were exposed before adoption or before anyone knew there was a risk. What matters most now is reducing future exposure, testing housemates, and working with your vet on a care plan that fits your cat’s health and your household.

Prevention starts with testing and lifestyle. Any new cat should be tested before entering a home with other cats. Cats that go outdoors, have contact with unknown cats, or live with FeLV-positive cats have higher exposure risk. Keeping cats indoors and preventing fighting are two of the most effective ways to reduce spread.

Vaccination is another important option for at-risk cats. VCA notes that FeLV vaccination is considered a core vaccine for kittens and one-year-old cats, and it may also be recommended for older cats based on lifestyle and exposure risk. Your vet will decide whether FeLV vaccination makes sense for your cat. Testing before vaccination is recommended because the vaccine does not help a cat that is already infected.

If one cat in the home is FeLV-positive, your vet may recommend testing all housemates, vaccinating exposed negative cats when appropriate, and separating cats if risk cannot be managed safely. Food bowls, litter boxes, and grooming contact matter less than the infected cat itself, so the prevention plan should focus on household structure and exposure rather than surface disinfection alone.

There is no cure that reliably removes FeLV from the body once a cat is persistently infected, so prognosis depends on the cat’s infection status, age, overall health, and whether complications develop. Some cats remain stable for years with few problems. Others become sick sooner because of anemia, severe infections, or FeLV-associated cancers. Merck notes an average survival time of about 2.4 years after diagnosis, but that is only an average and does not predict what will happen in one individual cat.

Recovery in FeLV cases usually means recovery from a specific complication, not recovery from the virus itself. For example, a cat may improve after treatment for a respiratory infection, dental inflammation, dehydration, or anemia. Ongoing monitoring is important because new issues can appear over time. Many FeLV-positive cats enjoy meaningful, comfortable lives when they are kept indoors, fed well, protected from stress, and seen promptly when symptoms change.

Quality of life should guide decisions. Some pet parents choose conservative monitoring and symptom-based care. Others pursue advanced testing or cancer treatment. Neither path is automatically right for every family. Your vet can help you weigh comfort, likely benefit, and cost range so the plan matches your cat’s needs and your goals.