What exactly is FIV and how is it different from feline leukemia?

Feline immunodeficiency virus is a species-specific lentivirus, part of the same viral family as HIV, that integrates into a cat's white blood cells and gradually degrades immune function over years rather than weeks (Cornell Feline Health Center, 2023). Unlike feline leukemia virus, FIV does not typically cause tumors directly, and infected cats often show no illness at all for long stretches. The Cornell Feline Health Center notes that FIV and FeLV are distinct viruses requiring separate blood tests, and a cat can be positive for one, both, or neither.

Prevalence data from a large surveillance study of North American veterinary clinics and shelters, coordinated through IDEXX Laboratories testing records, found FIV antibody positivity around 3.6% among tested cats, with rates notably higher in unneutered outdoor male cats due to bite-wound transmission during fights (American Association of Feline Practitioners, 2020). Indoor-only, spayed or neutered cats face a much lower lifetime risk of ever encountering the virus.

How do cats actually catch FIV, and can my other cats get it from sharing a litter box?

FIV is transmitted almost exclusively through deep bite wounds that introduce infected saliva directly into the bloodstream, which is why intact outdoor male cats involved in territorial fighting make up the highest-risk group (AAFP, 2020). Casual contact such as mutual grooming, sharing food bowls, sneezing, or using the same litter box carries a very low transmission risk because the virus does not survive well outside the body and isn't concentrated in those secretions.

Kittens born to FIV-positive queens can test positive for maternal antibodies without being truly infected, and the Cornell Feline Health Center recommends retesting kittens after 6 months of age once maternal antibodies have cleared to confirm true infection status (Cornell Feline Health Center, 2023). Multi-cat households with stable, non-aggressive relationships and no fighting can often safely mix FIV-positive and negative cats, though many veterinarians still advise separating them during introductions.

What are the first signs an owner might notice after infection?

In the acute phase, roughly one to two weeks after exposure, cats may develop a mild fever, swollen lymph nodes, and lethargy that often resolves on its own and gets mistaken for a passing bug (Merck Veterinary Manual, 2023). This is followed by a subclinical stage that can last for years, sometimes the cat's entire life, during which no outward symptoms appear at all despite ongoing viral replication.

When the disease eventually progresses toward feline acquired immunodeficiency syndrome, owners typically notice recurring problems rather than one dramatic symptom: chronic gingivitis and stomatitis, recurrent upper respiratory infections, persistent diarrhea, weight loss, and a dull, unkempt coat (Merck Veterinary Manual, 2023). Because these signs overlap with dozens of unrelated feline illnesses, veterinarians rely on testing rather than symptoms alone to confirm FIV involvement.

How do veterinarians test for and confirm an FIV diagnosis?

Most veterinary clinics screen with an in-house ELISA-based point-of-care test, such as the IDEXX SNAP FIV/FeLV Combo test, which detects antibodies against the virus from a small blood sample in about 10 minutes (American Association of Feline Practitioners, 2020). Because false positives can occur, especially in low-prevalence populations or vaccinated cats, the AAFP recommends confirming any positive screening result with a second test using a different method, such as Western blot or PCR testing at a reference laboratory like IDEXX or Antech.

Retesting matters most in kittens under 6 months old, cats with a low pretest probability of exposure (indoor-only, neutered), and any cat about to be euthanized for a positive result, since a single test alone should never be the basis for that decision (Cornell Feline Health Center, 2023). PCR testing can also help distinguish true infection from residual FIV vaccine antibodies in cats vaccinated before the vaccine was discontinued in the US in 2019.

What treatments are available, and is there a cure?

There is no cure that clears FIV from the body, and treatment instead focuses on managing secondary infections and complications as they arise rather than targeting the virus itself (Merck Veterinary Manual, 2023). Antiviral drugs used in human HIV treatment, including zidovudine (AZT), have shown some benefit in reducing viral load and improving stomatitis symptoms in FIV-positive cats, though use requires monitoring for bone marrow suppression and is typically reserved for cats with significant clinical signs.

Recombinant feline interferon omega, available in Europe and Japan though not currently FDA-approved in the US, has been studied for reducing severity of secondary infections in FIV-positive cats, according to research summarized by the American Association of Feline Practitioners (2020). Most day-to-day treatment instead means aggressive, prompt care of whatever opportunistic problem shows up, whether that's a dental infection, a respiratory virus, or a skin infection, since FIV-positive cats often need longer or more intensive courses than an FIV-negative cat would.

How should I care for an FIV-positive cat at home to keep them healthy long-term?

The single highest-impact change is keeping FIV-positive cats strictly indoors, which protects them from fights that could infect other cats, exposure to additional pathogens their weakened immune system handles poorly, and outdoor parasites and toxins (Cornell Feline Health Center, 2023). The AAFP also recommends veterinary checkups every 6 months rather than annually for FIV-positive cats, including bloodwork and a thorough oral exam, since dental disease is one of the most common and earliest complications.

Feeding a complete, balanced commercial diet and avoiding raw meat or unpasteurized dairy reduces exposure to bacterial and parasitic organisms that a compromised immune system may struggle to clear (Merck Veterinary Manual, 2023). Keeping vaccinations current with killed or recombinant (non-modified-live) vaccines, per your veterinarian's guidance, and prompt treatment of even minor illnesses helps prevent small problems from escalating in an FIV-positive cat.

What is the long-term outlook for a cat living with FIV?

Multiple studies cited by the Cornell Feline Health Center have found that FIV-positive cats with good management and no other major health conditions often live nearly as long as FIV-negative cats, commonly reaching 10 to 15 years of age (Cornell Feline Health Center, 2023). The subclinical phase can last for years or even the remainder of a normal feline lifespan, meaning many cats die of unrelated causes, like kidney disease or cancer, having never progressed to full-blown feline AIDS.

Progression risk rises with age, stress, and concurrent illness, so owners of FIV-positive cats are encouraged to treat every veterinary visit as an opportunity for early intervention rather than waiting for obvious decline (Merck Veterinary Manual, 2023). Quality of life for an FIV-positive cat in a stable indoor home with routine veterinary care is, in most cases, indistinguishable from any other cat's.