Feline Leukemia Virus (FeLV): Testing, Symptoms & Living With FeLV+

Last updated: May 6, 2026

A feline leukemia virus diagnosis can feel devastating. Many cat owners hear the word “leukemia” and immediately assume the worst. But FeLV is not a death sentence, and the reality of living with a FeLV-positive cat is far more hopeful than many people realize. Advances in veterinary medicine, improved testing methods, and a growing understanding of how the virus behaves have changed the outlook for FeLV+ cats dramatically over the past two decades.

Whether you have just learned that your cat tested positive, you are considering adopting a FeLV+ cat from a rescue, or you simply want to understand this common feline disease, this guide will walk you through everything you need to know — from how the virus spreads to practical daily care strategies that help FeLV-positive cats thrive.

What Is Feline Leukemia Virus?

Feline leukemia virus is a retrovirus that belongs to the same family as feline immunodeficiency virus (FIV). Once inside a cat’s body, FeLV inserts its genetic material into the DNA of the host’s cells — primarily targeting bone marrow cells, immune cells, and cells lining the intestinal tract. This integration is what makes the virus so difficult to eliminate: it essentially becomes part of the cat’s own genetic code in the affected cells.

Despite its name, feline leukemia virus does not always cause leukemia. The name comes from the virus’s ability to cause cancerous changes in white blood cells, but the actual disease presentation varies widely. FeLV can cause lymphoma (cancer of the lymphatic system), severe anemia, immune suppression that leaves cats vulnerable to secondary infections, and reproductive failure. Some cats carry the virus for years with minimal symptoms, while others develop life-threatening complications relatively quickly. The outcome depends largely on the stage of infection and the strength of the individual cat’s immune response.

Feline leukemia virus is species-specific. It cannot infect humans, dogs, or other animals — only domestic cats and some closely related wild felids are susceptible. There is absolutely no risk to you, your family, or your other non-feline pets from living with a FeLV-positive cat.

How Feline Leukemia Virus Spreads

FeLV is transmitted primarily through prolonged close contact between cats. The virus is shed in high concentrations in saliva, and to a lesser extent in nasal secretions, urine, feces, and milk. Understanding the routes of transmission is essential for preventing new infections and managing multi-cat households.

Mutual grooming and shared food bowls: Because saliva carries the highest viral load, cats who groom each other or eat and drink from shared bowls face the greatest risk of transmission. This is why FeLV spreads most readily among cats who live together and have friendly, close social relationships — an ironic reality that the most bonded cats face the highest risk.

Bite wounds: Deep bites that break the skin and introduce saliva directly into the bloodstream are an efficient route of transmission. Outdoor cats who fight over territory are at elevated risk, which is one of the many reasons veterinarians recommend keeping cats indoors.

Mother to kitten: Infected queens can transmit FeLV to their kittens during pregnancy through the placenta, during birth, or through nursing. Kittens infected in utero or during the neonatal period are at the highest risk of developing progressive infection because their immune systems are too immature to mount an effective defense.

Casual contact is low risk: FeLV is a fragile virus that survives only minutes to hours in the environment outside of a host. It is easily killed by common disinfectants, sunlight, and drying. Brief social interactions, passing contact, and sharing a household where cats do not groom each other or share food bowls pose minimal risk. The virus does not spread through the air over any meaningful distance.

The Three Stages of FeLV Infection

Not every cat exposed to feline leukemia virus becomes permanently infected. The outcome depends on the cat’s age, immune competence, viral dose, and the strain of virus involved. Veterinary science now recognizes three distinct outcomes of FeLV exposure, and understanding these stages is critical for interpreting test results and making care decisions.

Abortive infection: Some cats with robust immune systems are able to eliminate the virus completely before it ever reaches the bone marrow. These cats mount a strong immune response that neutralizes FeLV at the point of initial infection — typically in the lymphoid tissue of the oropharynx (the back of the throat). Cats with abortive infections never test positive on standard blood tests because the virus never establishes systemic infection. They develop immunity and are effectively protected from future exposure to the same strain. This outcome is most common in healthy adult cats.

Regressive infection (formerly called latent infection): In regressive infection, the cat’s immune system controls the virus and clears it from the bloodstream, but the viral DNA remains integrated into the bone marrow cells. These cats initially test positive on screening tests (SNAP tests) but eventually convert to negative as the immune system suppresses active viral replication. However, the proviral DNA — the viral genetic material embedded in the cat’s own DNA — remains present and can theoretically reactivate under severe immunosuppression, although this is uncommon. Cats with regressive infections are generally not contagious and can live normal, healthy lives. They may test positive on PCR-based tests that detect proviral DNA even though they are antigen-negative.

Progressive infection: In progressive infection, the virus overwhelms the immune system and establishes permanent, active infection in the bone marrow. These cats are persistently viremic — meaning the virus is actively replicating and circulating in the bloodstream at all times. They consistently test positive on both SNAP and IFA tests and are contagious to other cats. Progressive infection is the stage associated with the clinical diseases most people fear: lymphoma, severe anemia, immune suppression, and secondary infections. Progressive infection is most common in kittens, young cats, and cats with compromised immune systems. While the prognosis is more guarded, many cats with progressive infection still live for months to years with attentive care.

Testing for Feline Leukemia Virus: SNAP and IFA

Accurate testing is the foundation of FeLV management. Two primary testing methods are used in veterinary practice, and understanding the difference between them helps you interpret your cat’s results correctly.

SNAP test (ELISA-based screening): The SNAP test is the most commonly used initial screening tool for feline leukemia virus. It is an in-clinic blood test that detects the FeLV p27 antigen — a protein produced by the virus — in the bloodstream. Results are available within minutes, making it ideal for shelter intake screening, pre-adoption testing, and routine wellness checks. A positive SNAP test indicates that FeLV antigen is present in the blood at the time of testing. However, because some cats clear the virus during regressive infection, a single positive SNAP test does not necessarily mean permanent infection. Veterinarians typically recommend retesting positive cats after 30 to 60 days to determine whether the result persists or whether the cat’s immune system has cleared the antigenemia.

IFA test (immunofluorescent antibody test): The IFA test is a confirmatory test that detects FeLV antigen within white blood cells and platelets, indicating that the virus has infected the bone marrow. A positive IFA result strongly suggests progressive infection and persistent viremia. The IFA test requires a blood sample sent to an outside laboratory, so results take longer than the in-clinic SNAP test. In general, a cat that is positive on both SNAP and IFA testing is considered to have progressive, permanent FeLV infection. A cat that is SNAP-positive but IFA-negative may be in the early stages of infection or may have regressive infection and could potentially clear the virus.

PCR testing: Polymerase chain reaction testing detects the actual viral DNA (proviral DNA) in the cat’s cells. PCR can identify cats with regressive infection who are antigen-negative but still carry integrated viral DNA. While not used as a first-line screening tool, PCR testing can be valuable for resolving discordant SNAP/IFA results and for monitoring cats during the weeks after initial exposure.

When to test: All cats should be tested for FeLV at least once in their lives, ideally at the time of adoption or when first brought into a new home. Kittens should be tested regardless of the mother’s status. Any cat with an unknown history, any cat that has been exposed to an infected cat, and any cat showing symptoms consistent with FeLV-related disease should be tested promptly. If you are looking to adopt a cat, reputable rescues will test for FeLV before placing cats in adoptive homes.

Symptoms of Feline Leukemia Virus

Cats with regressive or abortive FeLV infections typically show no symptoms at all. Clinical signs appear primarily in cats with progressive infection, and even then, many cats remain asymptomatic for months to years before problems develop. When symptoms do appear, they tend to fall into several broad categories.

Immune suppression and secondary infections: FeLV’s attack on the immune system leaves cats vulnerable to infections that a healthy immune system would easily control. Recurring upper respiratory infections, chronic gingivitis and stomatitis (painful inflammation of the gums and mouth), persistent skin infections, and slow-healing wounds are all common presentations. These secondary infections are often the first sign that something deeper is wrong.

Anemia: Feline leukemia virus can cause severe, life-threatening anemia through multiple mechanisms. The virus can directly suppress red blood cell production in the bone marrow, trigger immune-mediated destruction of red blood cells, or cause abnormal red blood cell development. Signs of anemia include pale gums, lethargy, weakness, rapid breathing, decreased appetite, and poor exercise tolerance. FeLV-associated anemia can develop gradually or come on suddenly and may require blood transfusions in acute cases.

Lymphoma and other cancers: FeLV is the leading infectious cause of cancer in cats. The virus can induce lymphoma — cancer of the lymphatic system — in various locations throughout the body, including the intestines (alimentary lymphoma), the chest (mediastinal lymphoma), the kidneys (renal lymphoma), and the central nervous system. Leukemia — cancer of the white blood cells in the bone marrow — also occurs, though it is less common than lymphoma. Symptoms depend on the location and type of cancer and may include weight loss, vomiting, diarrhea, difficulty breathing, swollen lymph nodes, or neurological signs.

Weight loss and poor condition: Gradual weight loss, rough or unkempt coat, muscle wasting, and chronic poor body condition are common in FeLV-positive cats as the disease progresses. These changes may be subtle at first and easy to dismiss, which is why regular veterinary check-ups and monitoring body weight are so important.

Reproductive failure: Infected queens may experience infertility, fetal resorption, stillbirths, or give birth to kittens who are weak, fail to thrive, and often die within the first few weeks of life. This is why all breeding cats should be tested and confirmed negative before breeding.

Treatment for FeLV: Supportive Care Is Key

There is currently no cure for feline leukemia virus, and no antiviral medication has been proven to reliably eliminate the virus from cats with progressive infection. Treatment for FeLV is therefore focused on supportive care — managing symptoms, treating secondary conditions promptly, and maintaining the cat’s overall health and quality of life for as long as possible.

Treating secondary infections aggressively: Because FeLV-positive cats cannot fight off infections as effectively as healthy cats, any illness — even a seemingly minor one — should be treated promptly and thoroughly. This often means longer courses of antibiotics, antifungal medications, or other antimicrobials than would be necessary for an immunocompetent cat. Early intervention is critical; waiting to see if an infection resolves on its own is not appropriate for immunosuppressed cats.

Managing anemia: Cats with FeLV-associated anemia may benefit from nutritional support with iron-rich diets, erythropoiesis-stimulating agents in some cases, and blood transfusions when anemia becomes life-threatening. Regular monitoring of packed cell volume (PCV) through simple blood tests allows your veterinarian to track trends and intervene before anemia reaches a critical point.

Cancer treatment: FeLV-associated lymphoma can sometimes be managed with chemotherapy, and some cats achieve remission that lasts months to over a year. Chemotherapy in cats is generally well-tolerated with fewer side effects than humans experience. The decision to pursue chemotherapy should be made on a case-by-case basis in consultation with your veterinarian or a veterinary oncologist, weighing the cat’s overall condition, the type and location of the lymphoma, and the expected quality of life during treatment.

Immune-modulating therapies: Some veterinarians recommend interferon omega or other immune-modulating agents to support the immune function of FeLV-positive cats. While evidence for their efficacy is mixed and none is considered a cure, some cats do appear to benefit from these therapies as part of a comprehensive management plan.

Keeping FeLV-Positive Cats Healthy

The single most important thing you can do for a FeLV-positive cat is to be proactive about their health. Many FeLV+ cats live comfortably for years because their owners take a preventive, attentive approach to care.

Veterinary check-ups every six months: FeLV-positive cats should see the vet at least twice a year, rather than the once-a-year schedule recommended for healthy adult cats. These visits should include a thorough physical examination, complete blood count (CBC), and blood chemistry panel to catch problems like anemia, infection, or organ changes before they become emergencies.

High-quality nutrition: A nutritionally complete, high-quality diet is especially important for immunocompromised cats. Feed a well-balanced commercial cat food from a reputable manufacturer. Avoid raw diets entirely — raw meat, eggs, and unpasteurized dairy carry bacteria and parasites that a FeLV-positive cat’s immune system may not be able to handle. Good nutrition supports immune function, maintains healthy body weight, and contributes to overall vitality.

Parasite prevention: Keep FeLV-positive cats current on flea, tick, and intestinal parasite prevention. Parasites are an unnecessary burden on an already compromised immune system, and some — like Haemobartonella (now called Mycoplasma haemofelis) — can cause severe anemia in conjunction with FeLV infection.

Stress reduction: Chronic stress suppresses immune function in all cats, but the effects are amplified in FeLV-positive cats. Maintain a calm, predictable environment with consistent routines. Provide vertical space (cat trees, shelves), hiding spots, clean litter boxes, and regular interactive play. Minimize disruptions like loud noises, household renovations, and sudden changes in routine when possible.

Dental care: FeLV-positive cats are prone to severe gingivitis and stomatitis. Regular dental check-ups and professional cleanings when needed can prevent painful oral disease from developing into a chronic problem that affects eating, weight, and quality of life.

The Indoor-Only Requirement

FeLV-positive cats must live exclusively indoors. This is non-negotiable for two critical reasons.

First, keeping FeLV+ cats indoors protects other cats in the community. Because cats with progressive infection actively shed the virus in their saliva and other secretions, allowing them outdoors puts every unvaccinated or incompletely vaccinated cat in the neighborhood at risk. Responsible ownership means preventing the spread of this serious disease.

Second, the indoor environment protects the FeLV-positive cat. Outdoor cats face constant exposure to infectious agents — other viruses, bacteria, fungi, and parasites — that a healthy immune system handles routinely but that can cause severe, even fatal illness in an immunocompromised cat. Outdoor cats also face risks from traffic, predators, toxins, and extreme weather. A FeLV-positive cat’s best chance at a long, healthy life is within the safety of a well-enriched indoor home.

Indoor living does not mean a boring life. Window perches, cat trees, puzzle feeders, interactive toys, and dedicated daily play sessions provide mental stimulation and physical exercise that keep indoor FeLV+ cats happy and engaged. Some owners build secure outdoor enclosures (catios) that allow fresh air and sunshine without the risks of free roaming. You can explore different breeds and their adaptability to indoor living in our cat breeds directory.

FeLV in Multi-Cat Households

Managing feline leukemia virus in a home with multiple cats requires careful planning and honest conversation with your veterinarian. The primary goal is preventing transmission to uninfected cats while still giving the FeLV-positive cat a good quality of life.

Complete separation is ideal: The safest approach is to house FeLV-positive cats in a separate area of the home with their own food bowls, water bowls, litter boxes, bedding, and toys. The virus does not survive long in the environment and is killed by routine cleaning, so sharing a household (but not direct contact or shared items) is generally safe.

Vaccinate negative cats: All FeLV-negative cats in the household should be vaccinated against feline leukemia virus. While the vaccine is not 100 percent effective, it significantly reduces the risk of infection and provides an important safety net in case of accidental contact. Vaccination is discussed in more detail in the section below.

Test before introducing new cats: Any new cat entering a household with FeLV-positive cats — or any household at all — should be tested before introduction. A 30-day quarantine and retest protocol is recommended to catch cats who may be in the early window period of infection when the first test could be falsely negative.

Some families successfully house FeLV+ and FeLV-negative cats together: When separation is not practical, some families choose to house their cats together after ensuring all negative cats are fully vaccinated and understanding that some residual risk of transmission exists. This is a personal decision that should be made with full informed consent and veterinary guidance. Many multi-cat households manage this arrangement successfully for years.

The FeLV Vaccine

A vaccine against feline leukemia virus is available and is considered a core vaccine for kittens and at-risk adult cats by many veterinary organizations. The initial vaccination series consists of two doses given two to four weeks apart, with boosters administered annually or as recommended by your veterinarian based on risk assessment.

The FeLV vaccine is highly recommended for all kittens, outdoor cats, cats in multi-cat households (especially those with known FeLV-positive cats), and any cat with potential exposure to infected cats. For strictly indoor-only cats in single-cat households with no risk of exposure, some veterinarians consider the FeLV vaccine optional after the initial kitten series, though practices vary.

It is important to understand that the FeLV vaccine is not 100 percent protective. Vaccinated cats can still become infected if exposed to a high viral load or if their immune response to the vaccine is suboptimal. Vaccination reduces risk but does not eliminate it, which is why testing, indoor living, and avoidance of contact with known positive cats remain important components of prevention.

Cats should always be tested for FeLV before vaccination. Vaccinating a cat that is already FeLV-positive provides no benefit and is a waste of resources. Testing first also establishes a baseline status for future reference.

Lifespan With Feline Leukemia Virus

One of the most common questions from owners of newly diagnosed FeLV-positive cats is: how long will my cat live? The honest answer is that it varies enormously, and many of the statistics cited online are outdated or based on populations that did not receive modern supportive care.

Cats with regressive infection who clear the virus from their bloodstream can live completely normal lifespans and may never develop any FeLV-related health problems. These cats are, for all practical purposes, healthy cats who happen to carry dormant proviral DNA.

Cats with progressive infection have a more variable prognosis. Older studies suggested a median survival time of about two to three years after diagnosis, but these numbers came from an era before widespread vaccination reduced the overall prevalence of FeLV and before modern supportive care protocols were established. Many veterinarians today report FeLV-positive cats living five years or more after diagnosis with consistent, attentive care. Some cats with progressive infection live to advanced ages, particularly if they remain asymptomatic or develop only manageable complications.

The factors that most influence lifespan include the cat’s age at diagnosis (younger cats tend to have more guarded prognoses), the presence or absence of concurrent infections, the quality of ongoing veterinary care, nutrition, stress levels, and whether complications like lymphoma or severe anemia develop. Every cat is an individual, and broad statistical averages should not be used to predict the outcome for any single cat.

Adopting FeLV-Positive Cats: They Deserve Love

FeLV-positive cats are among the most overlooked animals in rescue. Many shelters historically euthanized cats immediately upon a positive FeLV test, and while practices have improved significantly, FeLV+ cats still wait far longer for homes than their negative counterparts. Some never find a home at all.

This is a tragedy, because FeLV-positive cats are just cats. They purr, they play, they curl up in your lap, they knock things off the counter, they chase laser pointers, and they form deep bonds with their humans. Their capacity for love and companionship is identical to any other cat. The only differences are that they need to stay indoors, they need more frequent vet visits, and they may need a bit more attentive care. For many owners, these are small prices to pay for the reward of sharing life with a wonderful animal.

If you are considering adoption, we encourage you to open your heart to a FeLV-positive cat. Many rescues, including Walk Me Home Rescue, believe that every cat deserves a chance at a loving home regardless of their FeLV status. Visit our adoption page to see cats currently looking for their forever families — including cats who happen to be FeLV-positive and are waiting for someone to see past the diagnosis to the amazing companion underneath.

Adopting a FeLV+ cat is particularly well-suited for single-cat households, households where all existing cats are already FeLV-positive or fully vaccinated, and homes where the owner is committed to indoor-only living and regular veterinary care. The adoption fees for FeLV+ cats are often reduced or waived, and the reward of giving a medically vulnerable cat a safe, loving home is immeasurable.

Frequently Asked Questions

Can I catch feline leukemia virus from my cat?

No. Feline leukemia virus is species-specific and cannot infect humans, dogs, or any other non-feline animals. You can safely cuddle, kiss, and share your home with a FeLV-positive cat without any risk to your own health or the health of non-cat pets in your household.

Should I euthanize my cat if they test positive for FeLV?

No. A positive FeLV test is not a reason for euthanasia. Many FeLV-positive cats live happy, comfortable lives for years with appropriate supportive care. Euthanasia should only be considered when a cat’s quality of life has deteriorated due to untreatable complications — the same standard that applies to any cat with any serious illness. A positive test result alone tells you nothing about how that individual cat will fare.

Can a cat test positive for FeLV and then test negative later?

Yes. Cats with regressive infection may initially test positive on a SNAP test when they are actively fighting the virus, then convert to negative once their immune system suppresses viral replication. This is why veterinarians recommend retesting positive cats after 30 to 60 days. A cat that converts from positive to negative has likely achieved regressive infection and may never develop clinical disease.

Is FeLV the same as FIV?

No. Feline leukemia virus and feline immunodeficiency virus are two different retroviruses with different modes of transmission, different disease courses, and different prognoses. FIV is primarily transmitted through deep bite wounds and tends to progress more slowly than FeLV. Both cause immune suppression, but they are distinct diseases requiring different management approaches. Cats can be infected with one, both, or neither.

How much does it cost to care for a FeLV-positive cat?

The day-to-day cost of caring for a FeLV-positive cat is similar to caring for any indoor cat: food, litter, and basic supplies. The main additional expense is more frequent veterinary visits — twice-yearly check-ups with bloodwork rather than annual visits. If complications arise, costs can increase, but many FeLV+ cats go years without needing anything beyond routine preventive care. Pet insurance that covers pre-existing conditions, wellness plans through your veterinary clinic, and low-cost veterinary clinics can all help manage costs.

Can FeLV-positive cats live with other cats?

Yes, with precautions. The safest approach is to keep FeLV-positive cats separated from negative cats or to ensure all negative cats are fully vaccinated against FeLV. Some families successfully house FeLV+ and negative cats together with vaccination and monitoring, though some residual risk of transmission remains. FeLV-positive cats can absolutely live together with other FeLV-positive cats without concern about reinfection.