Feline leukemia virus (FeLV) is a significant cause of illness and death in cats, particularly those with outdoor access. Vaccination, testing, and management protect both individual and population welfare.
FeLV causes significant welfare burden through immune suppression leading to repeated infections, anemia causing fatigue and weakness, and lymphoma causing pain and organ dysfunction. Progressive immune failure means FeLV-positive cats suffer disproportionately from illnesses that healthy cats would clear easily. Despite this, many FeLV-positive cats maintain good quality of life for years with appropriate management: regular monitoring, prompt treatment of secondary infections, and supportive care. Vaccination of uninfected cats in multi-cat households prevents spread. FeLV-positive cats should live indoors to prevent infection of other cats and to reduce their exposure to pathogens their compromised immune systems cannot handle. Welfare-conscious shelters increasingly place FeLV-positive cats in dedicated FeLV-positive foster or adoption programs rather than euthanizing them.