Feline Leukaemia Virus (FeLV): Welfare and Management

Feline leukaemia virus is a retrovirus that suppresses immune function in cats, leading to serious secondary infections, cancers, and significant welfare impacts.

Key Facts

FeLV is spread primarily through prolonged close contact, mutual grooming, shared food bowls, and bites.
Young kittens are most susceptible; adult cats have stronger natural resistance.
Approximately 2-3% of cats in the US are FeLV-positive; rates are higher in multi-cat households and outdoor cats.
Infected cats can be progressively infected (leading to persistent viraemia), regressively infected, or abortively infected.
Persistently viraemic cats have a median survival of 2-3 years after diagnosis.
Common outcomes include anaemia, lymphoma, secondary infections, and immune-mediated diseases.
Effective vaccines are available and recommended for cats with outdoor access.
FeLV-positive cats can live comfortably with good supportive care for extended periods.

Welfare Considerations

FeLV-positive cats face a range of welfare challenges depending on their infection status. Persistently infected cats experience progressive immune compromise, making them vulnerable to infections that healthy cats would easily resist. Each illness requires prompt treatment to minimise suffering. The emotional dimension for owners is significant — managing a terminal diagnosis in a beloved pet requires careful planning and honest veterinary communication. FeLV-positive cats should be kept indoors to protect both their own health (preventing infections) and other cats. Many FeLV-positive cats enjoy good quality of life for extended periods with attentive care and regular monitoring.

What You Can Do

Vaccinate cats with outdoor access against FeLV, especially before adopting new cats.
Test all new cats for FeLV before introducing them to a multi-cat household.
If your cat tests positive, keep them indoors and separated from FeLV-negative cats.
Work with your vet to establish a monitoring and supportive care plan.
Provide enrichment, warmth, and comfort to FeLV-positive cats to support quality of life.
Support shelters that provide appropriate housing and treatment for FeLV-positive cats rather than automatic euthanasia.