Companion Cats and Feline Leukemia Prevention

Feline leukemia virus causes immunosuppression, cancer, and anemia in infected cats — yet vaccination and testing can prevent transmission and manage population risk effectively.

Key Facts

FeLV affects approximately 2-3% of cats in the US but up to 13% in high-risk populations
The virus is transmitted through prolonged contact including mutual grooming and shared food bowls
FeLV causes immunosuppression making cats vulnerable to opportunistic infections and cancers
70% of infected cats clear the infection naturally within 16 weeks
Vaccination is highly effective for uninfected cats in high-exposure environments

Welfare Considerations

Cats with progressive FeLV infection experience chronic immune dysfunction — a state of persistent vulnerability to infections their immune system would normally control. Weight loss, anemia, and opportunistic disease cause progressive deterioration. The welfare timeline can span years of managed illness before quality of life declines to the point of humane euthanasia. Early testing allows informed management decisions; vaccination prevents new infections. The welfare burden of FeLV is largely preventable through testing and vaccination of cats in multi-cat or outdoor environments.

What You Can Do

Test cats for FeLV before introducing them to existing household cats
Vaccinate outdoor cats and those with exposure to unknown cats
Isolate FeLV-positive cats from FeLV-negative cats to prevent transmission
Monitor infected cats closely for opportunistic infections and treat promptly
Consult your veterinarian about quality of life management for FeLV-positive cats