Feline leukemia virus is a leading infectious cause of death in cats globally. Vaccination and testing provide effective protection for cats at risk of exposure.
FeLV welfare involves both the suffering caused by the disease itself and the complex management decisions for positive cats. FeLV-positive cats with progressive infection face eventual immunosuppression, anemia, and cancer — conditions causing significant suffering that require compassionate end-of-life management when quality of life declines. The welfare of FeLV-positive cats in multi-cat households is also complicated by the need for separation from FeLV-negative cats, which may cause social isolation stress. Modern management understanding recognizes that FeLV-positive cats can live comfortably for years with good supportive care including regular monitoring and prompt treatment of opportunistic infections. Vaccination of all at-risk cats prevents this disease entirely in most cases.