Feline leukemia virus is a retrovirus causing immunosuppression and cancer in cats, with welfare impacts ranging from mild to severe depending on infection status.
FeLV causes welfare compromise through progressive immunosuppression that increases susceptibility to opportunistic infections and eventually causes lymphoma in persistently viremic cats. Affected cats experience recurrent infections, poor body condition, anemia, and the systemic effects of lymphoma as disease progresses. The welfare timeline varies significantly - regressively infected cats may live normal lives while progressively infected cats face months to years of declining health. Welfare-centered management focuses on preventing secondary infections, maintaining nutrition, and providing appropriate treatment for complications. Quality of life monitoring guides decisions about when intensive treatment transitions to palliative care. Testing before adoption and vaccination of at-risk cats prevents new infections that would cause this welfare burden.