People usually look up feline leukaemia virus (FeLV) when a cat has tested positive, a new cat is joining the household, or there’s been a fight, bite, or long stretch of shared bowls and sleeping spots. The decision points are practical and time-sensitive: whether to vaccinate, whether to separate cats, and what a positive test really means.
FeLV is a cat-only retrovirus that can quietly reshape the immune system over months or years. Some cats live well for a long time with careful veterinary support, while others develop recurrent infections, anaemia, or certain cancers. Knowing how FeLV spreads, how testing works, and what “management” looks like helps you make calm, sensible choices.
What FeLV is (and what it isn’t)
FeLV (feline leukaemia virus) is a retrovirus that can cause immune suppression, anaemia, and increased risk of lymphoma and other illnesses. It doesn’t infect people, dogs, or other non-feline pets; the risk is between cats only.1
FeLV infection isn’t always a single, simple outcome. Some cats clear the infection before it establishes. Others develop persistent infection (often called “progressive” infection) and are more likely to become unwell over time. Because infection stage matters, one test on one day doesn’t always tell the whole story.2
How FeLV spreads
FeLV is most commonly spread through close, sustained cat-to-cat contact, with virus shed in saliva. Mutual grooming, sharing food and water bowls, and living in close quarters increases risk, as do bite wounds during fights (because saliva and blood can be involved).1
The virus doesn’t survive well in the environment, so transmission is usually about direct contact rather than “catching it from the house”. Good hygiene is still worthwhile in multi-cat homes, but separation and testing plans matter more than deep-cleaning routines.1
Cats at higher risk
- Kittens and young cats (more susceptible to infection).1
- Cats living in multi-cat households, shelters, or high-density colonies.1
- Cats with outdoor access, especially where there are roaming or stray cats.1
How common is FeLV in Australia?
Australian surveys suggest FeLV is less common than FIV overall, but it’s still present, and local rates vary by area and cat population. RSPCA Australia summarises nationwide estimates around ~2% (with variation by location).1
Signs to watch for
FeLV doesn’t have a single “signature” symptom. Illness often shows up as a pattern: problems that recur, linger, or arrive in clusters.
- Low energy, weight loss, reduced appetite
- Persistent or repeated infections (mouth, skin, respiratory, gut)
- Fever that comes and goes
- Pale gums (which can suggest anaemia)
- Enlarged lymph nodes
Many of these signs can also occur with other conditions, which is why testing matters rather than guesswork.
Diagnosis: what vets actually test for
The usual starting point is an in-clinic antigen test (often described as a “snap” test/ELISA) that detects FeLV p27 antigen in the blood. A positive result indicates antigen is present, but confirmatory testing is recommended, particularly if the cat is well or the result doesn’t fit the situation.2
Common follow-up options include:
- IFA (immunofluorescence assay): helps detect infection associated with bone marrow involvement (often aligning with more persistent infection), but performance can vary between laboratories and interpretation can be subjective.2
- PCR (often quantitative real-time PCR): detects proviral DNA and can help clarify infection stage when antigen results are unclear or changing over time.2
Because infection status can evolve (especially early after exposure), your vet may recommend repeating testing after an interval rather than relying on a single result.2
Treatment and management (what “no cure” really means)
There isn’t a simple cure that reliably eliminates FeLV from an infected cat. Management focuses on preventing avoidable infections, monitoring for complications early, and treating problems promptly when they appear.2
Evidence for antiviral or immune-modulating therapies is limited and many approaches are either early-stage, anecdotal, or not consistently effective in controlled field studies. If these treatments are considered, they’re best approached as case-by-case decisions with your veterinarian, with clear expectations and careful monitoring.2
What good ongoing care looks like
- Regular veterinary checks (often more frequent than for FeLV-negative cats) and routine blood/urine monitoring when advised.2
- Prompt treatment of secondary infections and dental disease, which can become persistent when immunity is compromised.2
- Parasite control and staying current with core vaccinations, guided by your vet.2
- Low-stress, stable routines and good nutrition (not a “special FeLV diet”, just consistent, balanced feeding that keeps weight steady).
Some FeLV-positive cats maintain good quality of life for years, while others decline sooner. Prognosis depends on infection stage, age, and what complications develop, so it’s normal for your vet to avoid a single, fixed timeline.2
Prevention: vaccination and practical risk reduction
FeLV vaccination is considered non-core: it’s recommended for cats with a meaningful risk of exposure (for example, outdoor access, shelters, or high-density multi-cat settings). Vaccination decisions should be based on lifestyle, not fear.3
Most guidelines recommend testing for FeLV before vaccination, because vaccinating an already-infected cat won’t prevent infection or stop transmission.3
Risk reduction that makes a real difference:
- Keep cats indoors (or use secure outdoor enclosures) to reduce contact with unknown cats.
- Prevent fighting: desexing, slow introductions, and careful resource set-up in multi-cat homes.
- Test new cats before introducing them to resident cats.2
Living with an FeLV-positive cat
In a quiet household, FeLV-positive cats often settle into a normal rhythm: eating, sleeping, grooming, watching the world from a window. The key is lowering exposure to infections and avoiding situations where FeLV could spread to other cats.
Household rules that protect everyone
- Keep the FeLV-positive cat indoors to reduce exposure to infectious disease and to prevent virus spread to other cats.2
- If you have other cats: speak with your vet about testing schedules and FeLV vaccination for in-contact cats, and whether separation is needed (especially if cats groom each other or occasionally fight).2
- Set up resources sensibly (multiple feeding and resting spots) to reduce tension and fighting, which lowers bite risk.1
Myths and misconceptions
“FeLV is a death sentence.”
FeLV is serious, but outcomes vary. Some cats become unwell quickly; others remain well for extended periods with attentive preventive care and early treatment of secondary problems.2
“FeLV spreads to humans or dogs.”
FeLV is a cat-only virus. It doesn’t infect people, dogs, or other non-feline pets.1
“Indoor cats never need to think about FeLV.”
Indoor living lowers risk sharply, but cats can still be exposed when a new cat enters the household, through fostering, or after an escape. Testing new arrivals and making vaccination decisions based on real exposure risk is the safer approach.2
Final thoughts
FeLV is best handled the way wildlife handles bad seasons: with steady routines, good shelter, and careful observation. If your cat has been exposed, or you’re planning introductions in a multi-cat home, talk to your vet about testing, confirmatory steps when results are unclear, and whether FeLV vaccination makes sense for your cat’s lifestyle.2
References
- RSPCA Australia Knowledgebase: What are FIV and FeLV?
- Merck Veterinary Manual: Summary of clinical management of feline leukaemia virus
- WSAVA Vaccination Guidelines for Dogs and Cats (includes FeLV vaccination guidance)
- WSAVA Vaccination Guidelines Group (VGG) compiled recommendations (FeLV schedules and notes)
- Merck Veterinary Manual: FeLV testing flowchart (adapted from AAFP guidelines)
- Merck Veterinary Manual: FeLV quantitative testing (ELISA and PCR by infection stage)
- Merck Veterinary Manual: Serologic test kits (FeLV testing and vaccination note)
- University Veterinary Teaching Hospital Sydney: Cat vaccinations (includes FeLV vaccine as risk-based)
Veterinary Advisor, Veterinarian London Area, United Kingdom