FeLV / FIV (Feline Leukemia / Feline Immunodeficiency Virus)
Two viral infections in cats that weaken the immune system; testing and vaccination are recommended for multi-cat households and cats that go outdoors.
What Are FeLV and FIV
FeLV (feline leukemia virus) suppresses the immune system and increases the risk of developing tumors; FIV (feline immunodeficiency virus) works similarly to human HIV, gradually breaking down the immune system, but the latency period can last for years, during which an infected cat may show no symptoms at all for a long time.
How It Spreads
Mainly spread through close cat-to-cat contact, such as sharing food bowls or mutual grooming (FeLV), or bite wounds (FIV is more commonly spread through fighting bites). Cats that only have occasional contact through a window screen, without close interaction, have relatively low infection risk.
Prevention and Caring for a Carrier Cat
Kittens are recommended to get the FeLV vaccine (especially if they'll go outdoors or live in a multi-cat household); new cats should be tested for FeLV/FIV before joining the household to avoid infecting other cats. A confirmed carrier isn't a death sentence — many carrier cats can maintain years of stable quality of life with regular health checkups, avoiding fights/bite wounds with other cats, and good nutrition.
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Sources:
- Cornell Feline Health Center
- American Association of Feline Practitioners（AAFP）
This site is for general reference only and is not a substitute for veterinary diagnosis. If your cat shows unusual signs, please see a vet promptly.