Feline leukemia virus is a serious retroviral disease of cats that causes immunosuppression, cancer, and death — but is largely preventable through vaccination.
FeLV causes progressive, serious suffering in progressively infected cats. Immune suppression leaves affected cats vulnerable to infections that would not affect healthy animals — recurrent respiratory, dental, and gastrointestinal infections cause chronic suffering. Lymphoma — the most common cancer caused by FeLV — causes weight loss, lethargy, enlarged lymph nodes, and pain. Anemia from bone marrow suppression causes weakness and breathlessness. Despite this serious welfare burden, FeLV is largely preventable through vaccination and testing. Multi-cat households that fail to test new additions and vaccinate residents create conditions for virus spread. FeLV-positive cats can be managed humanely — keeping them indoors, preventing stress, and treating secondary infections promptly significantly extends quality life expectancy.