Feline leukemia virus (FeLV) is a retrovirus that compromises cats' immune systems, causing a range of serious diseases — but management has improved dramatically with vaccination and early diagnosis.
FeLV-positive cats face real welfare challenges, but a diagnosis is not an immediate death sentence. Cats with regressive or latent infection may live normal lifespans with no clinical signs. Those with progressive infection eventually develop lymphoma, anemia, or opportunistic infections that require careful monitoring and palliative management. Pain management, nutritional support, and infection prevention (keeping FeLV+ cats indoors away from immunocompromised cats) significantly support quality of life. Shelters have historically euthanized FeLV-positive cats, but growing evidence supports adoption programs with proper management. Multi-cat households should test all cats and separate FeLV-positive individuals to prevent transmission and reduce their stress.