Research overview: FIV and FeLV coinfection and immune consequences

Cats can be simultaneously infected with FIV and feline leukemia virus, and coinfection tends to accelerate immune decline and worsen prognosis compared with either virus alone. The two retroviruses differ in transmission and biology but both compromise immune defenses, raising susceptibility to opportunistic infections, anemia, and neoplasia. Retrovirus screening guidelines therefore recommend testing for both. This overview gathers findings across the coinfection literature rather than one source, describing how the viruses interact within the immune system, why dual-positive cats need closer monitoring and prompt treatment of secondary problems, and why combined point-of-care tests became standard practice for new cats, sick cats, and shelter intake protocols worldwide.