If you're a cat parent, you may have heard of FIV, but what is it? FIV is short for feline immunodeficiency virus, which is an infectious retroviral disease in cats. FIV is a lot like HIV in humans: It attacks a cat's immune system, weakening it over time and leaving them vulnerable to secondary infections. Once a cat is infected with FIV, they're infected for life.
Keep reading to learn more about FIV, including its signs, how to prevent the virus in your cat and how FIV treatment works.
Signs of FIV
FIV is a slow attacking virus; it can take years for signs to appear. Furthermore, an FIV-infected cat may get sick and then get progressively worse or may only show signs of the virus sporadically.
When signs of FIV do appear, they're due to secondary infections. Because FIV weakens a cat's immune system, they become susceptible to other illnesses.
Signs vary widely and may include:
- Enlarged lymph nodes
- Fever
- Loss of appetite and weight loss
- Unkempt hair or coat
- Vomiting or diarrhea
- Sneezing or runny, swollen eyes
- Non-healing wounds
- Severe gum inflammation
- Skin redness or sores
- Abnormal litter box behavior, such as frequent urination, straining, urinating outside the box and/or bloody urine

A cat that's infected with FIV can only pass on the virus to other cats — not to humans or other animals. It usually spreads via bite wounds. FIV can also be transmitted in utero to kittens through their mother's placenta.
Diagnosing FIV
Based on historical data, FIV-positive cats are most likely an outdoor, male cat that fights or has bite wounds. They're typically feral, stray and not neutered.
FIV is diagnosed through a quick blood test. Make sure to have a cat tested for FIV before bringing them into your household. Also, keep in mind that kittens younger than 6 months who test positive may not actually be infected. These kittens should be isolated from other cats and tested again once maternal antibodies clear from their system; this usually occurs at around 6 to 7 months of age.
No test is 100% accurate, so consult with your veterinarian to determine whether your cat needs additional testing.
What Is FIV Prevention?
There was an FIV vaccine available until 2017, but it was discontinued for multiple reasons. The easiest way to prevent FIV in your cat is to keep them inside and away from cats that could infect them. If you choose to let your cat outside, keep them on a leash or in an outdoor enclosure (like a cat patio).