What FIV Is
Feline immunodeficiency virus, or FIV, is a retrovirus that gradually weakens a cat’s immune system, making it a feline relative of HIV in humans, though it cannot be transmitted between species.
Once a cat is infected, the virus remains in the body for life, and while many FIV-positive cats stay healthy for years, the virus slowly reduces the immune system’s ability to fight off other infections over time.
FIV progresses through stages similar to other chronic viral infections: an initial acute phase with mild symptoms, followed by a long asymptomatic phase that can last many years, and eventually a more advanced immunodeficiency stage in some cats.
It’s a distinct virus from feline leukemia virus (FeLV), and while cats can be infected with both, they’re diagnosed and managed somewhat differently since they affect the immune system in different ways.
How It Spreads
FIV is transmitted primarily through deep bite wounds, which is why it’s most common in unneutered outdoor male cats that fight over territory or mates.
It’s not typically spread through casual contact like sharing food bowls, mutual grooming, or litter boxes, which means FIV-positive and FIV-negative cats can often live together safely in the same household with some precautions.
Mother-to-kitten transmission can occur during birth or through nursing, though it’s less common than bite-wound transmission and happens more often when the mother has a high viral load.
Because the main risk factor is fighting, keeping cats indoors and spaying or neutering them significantly reduces the chance of FIV transmission at the population level.
Symptoms & Stages
During the acute phase, which occurs weeks after infection, cats may show mild, easy-to-miss symptoms like fever, swollen lymph nodes, or lethargy that often resolve on their own without treatment.
The asymptomatic phase can last for years, sometimes for a cat’s entire life, during which an infected cat may show no outward signs of illness at all despite carrying the virus.
As the immune system weakens over time, cats become more prone to secondary infections such as chronic gum disease, upper respiratory infections, skin infections, and slow wound healing.
In advanced cases, cats may experience weight loss, persistent fever, chronic diarrhea, or neurological changes, though many FIV-positive cats never reach this stage with good preventive care.
Diagnosis & Testing
FIV is typically diagnosed with a blood test that detects antibodies to the virus, and this same combination test panel usually screens for FeLV at the same time during a standard wellness visit.
A positive result in kittens under six months old should be confirmed with a follow-up test later, since maternal antibodies passed through nursing can cause a temporary false positive in young kittens.
Because no single test is completely infallible, vets often recommend confirming a positive result with a second, different type of test (such as a PCR test) before making major decisions about a cat’s care or living situation.
Routine testing is especially important for cats with outdoor access, unknown backgrounds, or bite wound histories, as well as before introducing a new cat into a multi-cat household.
Managing an FIV-Positive Cat
Keeping an FIV-positive cat indoors protects both the infected cat from additional infections and other cats from potential exposure through fighting.
Routine veterinary checkups, typically every six months rather than annually, allow for earlier detection of secondary infections or health changes before they become serious.
A high-quality diet, a low-stress environment, and prompt treatment of any illness — even minor ones — all help support an FIV-positive cat’s immune system over the long term.
Many FIV-positive cats live full, symptom-free lives for a decade or more with appropriate care, and their diagnosis alone shouldn’t be treated as a reason to withhold adoption or euthanize an otherwise healthy cat.
Frequently Asked Questions
Can FIV be cured?
There is no cure for FIV, but it’s a manageable chronic condition, and many infected cats live long, comfortable lives with routine veterinary care and a stable indoor environment.
Can FIV-positive cats live with FIV-negative cats?
Yes, in stable multi-cat households without ongoing fighting, the risk of transmission through casual contact is low, though introducing cats slowly and monitoring for aggression is still recommended.
Can humans catch FIV from a cat?
No, FIV is species-specific and cannot infect humans or other non-feline animals, despite being related to HIV.
Is there a vaccine for FIV?
A vaccine was previously available in some regions but has been discontinued in most markets, and prevention today relies mainly on keeping cats indoors and reducing fighting through spaying and neutering.
How long can a cat live with FIV?
Many FIV-positive cats live 10 years or longer after diagnosis, especially with indoor living, regular vet visits, and prompt treatment of secondary infections.