Cat Feline Leukemia Virus Welfare

Feline leukemia virus (FeLV) remains a serious cause of morbidity and mortality in cats; vaccination and testing protect individual and population welfare.

Key Facts

FeLV is a retrovirus transmitted primarily through saliva, mutual grooming, and shared food and water bowls.
Approximately 0.5-2% of healthy cats in Britain are FeLV positive; rates are higher in outdoor cats and cat colonies.
FeLV causes immunosuppression, anaemia, lymphoma, and other cancers, significantly reducing lifespan.
Vaccination is highly effective and is recommended for cats at risk of exposure.
Persistently viraemic cats remain infectious to other cats throughout their lives.

Welfare Considerations

FeLV-positive cats may live for several years before developing disease, but their welfare is threatened by progressive immunosuppression that causes recurrent infections, anaemia, and ultimately cancer. The welfare management of FeLV-positive cats focuses on preventing secondary infections, monitoring for disease development, indoor housing to prevent transmission and reduce exposure to other pathogens, and palliative care as disease progresses. Euthanasia decisions for FeLV-positive cats with advanced disease follow standard quality-of-life assessment. Testing new cats before introducing them into multi-cat households prevents transmission to susceptible individuals.

What You Can Do

Test all new cats for FeLV before introducing them into your home or household.
Vaccinate outdoor cats and those with exposure to unknown cats against FeLV.
Keep FeLV-positive cats indoors to prevent transmission and reduce secondary infection risk.
Maintain excellent husbandry and veterinary monitoring for FeLV-positive cats to detect disease early.