Feline Leukemia Virus (FeLV): Symptoms, Testing & Treatment

Quick Answer
  • Feline leukemia virus (FeLV) is a contagious retrovirus that can suppress the immune system, damage bone marrow, cause anemia, and increase the risk of lymphoma and leukemia.
  • Many cats have no signs early on. When illness develops, common clues include weight loss, poor appetite, recurring infections, pale gums, fever, mouth inflammation, and low energy.
  • Testing usually starts with an in-clinic ELISA blood test. Positive or unclear results often need confirmation and, in some cats, repeat testing in about 30 days to clarify whether infection is progressive or regressive.
  • There is no cure that clears FeLV from the body, but many FeLV-positive cats can live comfortably for months to years with indoor living, routine monitoring, fast treatment of secondary illness, and a care plan tailored by your vet.
Estimated cost: $150–$4,000

What Is Feline Leukemia Virus (FeLV)?

Feline leukemia virus, or FeLV, is a contagious retrovirus that infects cats and can affect the immune system, blood-forming tissues, and cancer risk. Despite the name, it does not always cause leukemia. FeLV is also linked to anemia, chronic infections, poor healing, and cancers such as lymphoma.

After exposure, cats do not all respond the same way. Some cats eliminate the virus before it becomes established. Others develop a regressive infection, where viral genetic material remains in the body but active virus is not consistently found in the blood. Cats with progressive infection continue to carry and shed the virus and are at the highest risk for FeLV-related illness.

FeLV is still one of the most important infectious diseases in cats, even though testing and vaccination have reduced how common it is. It affects roughly 2% to 3% of cats in the United States and Canada overall, but rates are much higher in sick cats and cats with higher exposure risk. FeLV does not infect people or dogs.

A positive FeLV result is serious, but it is not always an immediate crisis. Some cats remain stable for long periods. The goal is not to chase one perfect plan. It is to work with your vet on a realistic monitoring and treatment strategy that fits your cat's health, household, and your family's resources.

Symptoms of Feline Leukemia Virus

  • No symptoms at first; some cats appear normal for months before illness develops
  • Weight loss or poor body condition, even with a normal appetite early on
  • Low energy, hiding more, or reduced play and grooming
  • Recurring infections such as upper respiratory, skin, ear, urinary, or dental infections
  • Pale gums from anemia, which can become urgent if weakness or fast breathing develops
  • Fever that keeps returning or does not have an obvious cause
  • Poor coat quality, patchy grooming, or slow healing
  • Mouth pain, gingivitis, or stomatitis causing drooling, bad breath, or trouble eating
  • Vomiting, diarrhea, or chronic digestive upset
  • Enlarged lymph nodes, breathing changes, or abdominal swelling, which can raise concern for lymphoma or other complications

FeLV can be a quiet infection at first, so the pattern matters as much as any one symptom. A cat that keeps getting sick, loses weight slowly, or never seems to fully bounce back after treatment deserves a closer look. See your vet promptly if your cat has pale gums, trouble breathing, marked weakness, stops eating, or develops swelling, because those signs can point to anemia, severe infection, or cancer-related complications.

How Do Cats Get Feline Leukemia?

FeLV spreads mainly through close, repeated contact with an infected cat. The virus is shed most heavily in saliva, but it can also be present in nasal secretions, urine, feces, and milk. Common routes include mutual grooming, shared food and water bowls, shared litter areas in close-contact homes, and bite wounds.

Mother cats can also pass FeLV to kittens before birth or while nursing. Kittens are more vulnerable than adults because their immune systems are less mature. Adult cats can still become infected, especially if they go outdoors, fight with other cats, or live with cats whose FeLV status is unknown.

FeLV does not survive well outside the body. Under normal household conditions, it usually lasts only a short time in the environment and is readily inactivated by routine cleaning and disinfectants. That means transmission is much more about cat-to-cat contact than contaminated rooms or furniture.

Risk is highest in cats that go outdoors unsupervised, live in multi-cat homes with an FeLV-positive cat, come from shelters or rescue situations with unknown testing history, or have a history of bite wounds. Testing new cats before introduction is one of the most practical ways to reduce household spread.

How Is FeLV Diagnosed?

Testing usually begins with an ELISA antigen test, often called a snap test, performed on a small blood sample in your vet's office. This test looks for FeLV antigen in the bloodstream and is commonly used for screening newly adopted cats, sick cats, cats with unknown status, and cats before they join a household with other cats.

A positive screening result should not always be treated as the final answer on the same day. Your vet may recommend a confirmatory test or repeat testing in about 30 days, especially if the cat feels well or the exposure history is unclear. This helps sort out whether the cat has a transient early infection, a regressive infection, or a progressive infection.

Additional workup often includes a complete blood count, chemistry panel, and urinalysis. These tests do not diagnose FeLV by themselves, but they help your vet look for anemia, low white blood cells, dehydration, organ stress, and secondary infections. If your cat has enlarged lymph nodes, weight loss, breathing changes, or abdominal changes, imaging or needle samples may be recommended to check for lymphoma or other complications.

Testing is recommended for all newly adopted cats, cats entering a home with other cats, cats with bite wounds, and any cat with unexplained illness. Even indoor cats may need testing if their history is unknown or if another cat in the home tests positive.

Treatment Options for FeLV-Positive Cats

Spectrum of Care means you have options. Here are treatment tiers at different price points.

Conservative Care

$150–$700
Best for: Cats that feel well, newly diagnosed cats, or families who need a practical monitoring plan focused on comfort, prevention, and early detection
  • Initial FeLV screening and confirmation plan
  • Baseline exam plus CBC and chemistry panel
  • Indoor-only lifestyle and separation from FeLV-negative cats when appropriate
  • Good nutrition, parasite prevention, and stress reduction
  • Prompt treatment of secondary infections when they appear
  • Follow-up exams every 6 to 12 months, depending on your vet's recommendations
Expected outcome: Variable. Some cats remain stable for years, especially if they are otherwise healthy at diagnosis and complications are caught early.
Consider: This approach does not target advanced complications aggressively. Costs are lower up front, but flare-ups such as infections, anemia, or dental disease can still create unplanned visits.
Most Common

Standard Care

$700–$1,800
Best for: Most FeLV-positive cats, especially those with intermittent symptoms or pet parents who want a proactive plan without jumping straight to specialty care
  • Repeat FeLV testing when indicated to clarify infection status
  • Wellness exams about every 6 months
  • Routine CBC, chemistry, and urinalysis monitoring
  • Dental and oral pain evaluation if gingivitis or stomatitis develops
  • Targeted treatment for infections, anemia, dehydration, nausea, or appetite loss
  • Imaging or cytology if weight loss, enlarged lymph nodes, or organ changes are found
Expected outcome: Fair to good for many cats in the short to medium term. Regular monitoring can improve comfort and catch treatable complications sooner.
Consider: Requires ongoing visits and lab work. Some cats still progress despite careful care, and repeated testing or diagnostics can add to the total cost range over time.

Advanced Care

$1,800–$4,000
Best for: Cats with serious complications such as lymphoma, severe anemia, repeated hospital-level illness, or families who want access to specialty options
  • Hospitalization for severe anemia, dehydration, infection, or poor appetite
  • Blood transfusion when life-threatening anemia develops
  • Ultrasound, radiographs, or tissue sampling for suspected lymphoma or organ disease
  • Oncology or internal medicine consultation
  • Chemotherapy or other cancer-directed treatment when FeLV-related lymphoma is diagnosed
  • Case-by-case use of antiviral or immune-modulating therapies under close veterinary supervision
Expected outcome: Guarded and highly dependent on the complication being treated. Some cats with lymphoma or severe inflammatory disease can gain meaningful time and comfort with advanced care.
Consider: Higher cost range, more appointments, and more intensive monitoring. Not every cat is a good candidate, and quality-of-life discussions remain central throughout treatment.

Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.

Questions to Ask Your Vet About FeLV

Bring these questions to your vet appointment to get the most out of your visit.

  1. What test was used, and does my cat need confirmatory or repeat testing? A single screening result may not tell the whole story, especially early after exposure.
  2. Do my cat's exam findings or lab results suggest progressive infection, anemia, or another complication right now? This helps you understand what is happening today, not only the diagnosis label.
  3. How often should we repeat blood work and wellness visits for my cat's current stage? Monitoring intervals vary depending on whether your cat is stable, newly diagnosed, or already showing signs.
  4. What symptoms at home should make me call the same day or seek urgent care? FeLV complications can worsen quickly, and clear thresholds help you act sooner.
  5. Can my FeLV-positive cat safely live with my other cats, and what testing or vaccination should the others have? Household management is one of the most important parts of prevention.
  6. If my cat stops eating or develops mouth pain, what supportive care options do we have? Appetite loss and oral disease are common quality-of-life issues in FeLV-positive cats.
  7. If lymphoma or severe anemia develops, what are our conservative, standard, and advanced treatment options? This keeps the conversation practical and helps you plan ahead without pressure.
  8. What is a realistic outlook for my cat over the next 6 to 12 months? A time-based prognosis can be easier to use for planning than a single broad statement.

How to Prevent Feline Leukemia Virus

Testing is the starting point for prevention. Test all new cats before they join your household, and ask your vet whether repeat testing is needed after a recent exposure. If one cat is FeLV-positive and others are negative, your vet can help you decide whether separation, vaccination, or both make the most sense for your home.

The FeLV vaccine is recommended for all kittens, and for adult cats with meaningful exposure risk, such as cats that go outdoors or live with cats of unknown status. Vaccination lowers risk but does not replace testing and exposure control. A vaccinated cat can still become infected in some situations.

Keeping cats indoors is one of the most effective ways to reduce FeLV exposure. It also protects FeLV-positive cats, who are more vulnerable to infections and injuries. Avoid introducing untested cats into the home, and do not assume a healthy-looking cat is FeLV-negative.

If your cat is FeLV-positive, focus on reducing stress, maintaining routine veterinary care, and preventing spread to other cats. Many FeLV-positive cats enjoy a good quality of life when their environment is stable and medical problems are addressed early.

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