Feline immunodeficiency virus and feline leukemia virus cause progressive immune disease in cats, but many FIV-positive cats can live long, comfortable lives with appropriate management.
FIV and FeLV create welfare challenges primarily through secondary illness from immune suppression — opportunistic infections, dental disease, anemia, and cancer. However, the welfare impact is highly variable: FIV-positive cats kept indoors with good nutrition and regular veterinary care often experience minimal illness for years. A major welfare concern is inappropriate euthanasia of healthy FIV-positive cats at shelters based on outdated protocols. Modern shelter medicine guidance recommends that FIV status alone not be grounds for euthanasia. FeLV-positive cats require more active management but can also have meaningful quality of life with appropriate veterinary care and supportive housing. Pain management for secondary illness and regular monitoring are key welfare interventions.