What is Feline Immunodeficiency Virus?

7 min read
7 min read

Updated - Sep 15th, 2022

Key Points

  • Feline immunodeficiency virus, commonly known as FIV, is a virus that attacks and weakens a cat’s immune system.
  • Symptoms that result from FIV are usually from secondary conditions developed due to a weakened immune system. Your vet may prescribe medications to treat these secondary conditions.
  • While FIV is incurable, cats living with FIV can still lead long and happy lives.

Feline immunodeficiency virus (FIV) is a serious condition that weakens a cat’s immune system.

If your cat was recently diagnosed with feline immunodeficiency virus, or you fear they may have the virus, take a deep breath. Although FIV is a serious condition, a diagnosis does not mean your cat can’t go on to lead a long and happy life. Although there is no cure, many cats live with FIV symptom-free for months or even many years. Read on for some key facts about FIV and how to care for a cat with FIV.      


FIV can be present in a cat’s system for years without the cat showing any signs of illness at all. Usually, when cats develop symptoms, they have moved into the final stage of FIV, sometimes called feline AIDS. These symptoms are not symptoms of FIV itself but rather symptoms of secondary conditions your cat developed as a result of their weakened immune system. Here are some clinical signs to look out for:

  • Weight loss
  • Anemia
  • Stomatitis/gingivitis (diseases that cause a cat’s gums and mouth to become inflamed)
  • Fever
  • Loss of appetite
  • Diarrhea
  • Excessive shedding/poor coat condition
  • Inflammation
  • Swollen lymph nodes
  • Recurring infections
  • Changes in behavior

Cats in the last stage of FIV often develop cancers or other terminal conditions.


FIV is passed primarily through bite wounds from infected cats. FIV-positive cats carry the disease in their saliva, so when they bite other cats, infected saliva can enter the cat’s bloodstream.


When cats contract an FIV infection, they develop antibodies to combat the virus. Vets diagnose FIV by checking if antibodies are present in a cat’s blood. 

Vets typically use a methodology called ELISA (enzyme-linked immunosorbent assay) to test cats for FIV antibodies. To perform this test, the vet will draw a blood sample and mix it with absorbent plates containing enzymes that seek out antibodies. These enzymes then attach to FIV antibodies, if any are present within your cat’s system.

Unfortunately, FIV testing is not foolproof. There is a possibility that false positives or false negatives can occur. If your cat tests positive, your vet will likely retest your cat eight weeks after the initial result. Your vet may also recommend a different type of test: either a Western blot or PCR test to help confirm the positive result.

Young kittens sometimes receive maternal antibodies through an infected mother cat’s milk. As a result, these kittens may test positive for FIV. These kittens usually test negative once they stop drinking their mother’s milk. If a kitten under four months of age tests positive for FIV, retest a few months later to determine if the antibodies are still present.

It takes a little while after infection for cats to build up antibodies. If your cat was recently bitten by another cat with an unknown medical history, wait a couple of months before testing to avoid a false negative.


Currently, there is no cure for feline immunodeficiency virus. However, cats infected with FIPV can still lead long and happy lives. Care for cats diagnosed with FIV consists of regular vet visits to monitor symptoms and virus progression. Vets also may treat secondary conditions. Your vet may suggest:

  • Antibiotics for bacterial secondary infections
  • Anti-inflammatory medications
  • Immune-stimulating medications
  • Electrolyte replacement therapy
  • Diet changes

Occasionally, vets treat cats with the antiviral drug zidovudine (AZT), a medication developed to treat HIV in humans.

Your vet will help you determine the best course of action. Oftentimes, FIV-positive cats who are asymptomatic will not require any treatment at all.

Recovery and care

Once your cat has been diagnosed with FIV, keep them isolated from non-infected cats to avoid spreading the virus. Keeping your cat away from others is also a good idea for their own health because it reduces the likelihood of them encountering germs that could cause serious illness due to their weakened immune system.

Your vet will help you determine the best course of action for continued care. Generally, vets recommend you feed your cat high-quality food and keep their environment clean and sanitized. Some vets recommend you avoid feeding your infected cat raw food, as raw food has a higher potential for contamination and may contain pathogens that could cause illness.

If your immunocompromised cat does become sick, take action right away. With a weakened immune system, your cat is at a higher risk for developing complications and severe symptoms, even when it comes to common illnesses.

Infected cats should return to the vet every six months to monitor FIV progression. At these visits, the vet will perform urine and blood tests and assess your cat’s overall health, making changes to your treatment plan as needed.


There is currently no FIV vaccine available. The best way to prevent your cat from contracting FIV is to keep your cat inside and away from outdoor cats that could be carrying the virus. If you do take your cat outside, consider using a leash. Since FIV spreads primarily through bite wounds, cats who see large groups of other cats, especially those prone to fighting, are more at risk of infection. The virus is most prevalent in male cats who are not neutered.

If you are bringing a new cat into your home, it’s a good idea to test them for FIV beforehand to avoid the potential spread to your other cats.

If a female cat is diagnosed with FIV, your vet may recommend spaying your cat to prevent her from potentially spreading the virus to offspring.

What to expect at the vet’s office

When you arrive at your vet’s office, your vet will check your cat’s vitals and ask about your cat’s symptoms and previous medical history. Then, your vet will draw a blood sample to perform an ELISA test for FIV antibodies. If your cat receives a positive test result for FIV antibodies, your vet will likely schedule a follow-up exam in a few weeks to test again for accuracy.

The bottom line

If your furry friend has been diagnosed with FIV, they can still have a high quality of life and live for years to come. Talk to your vet to develop a care plan.


Does pet insurance cover feline immunodeficiency virus?

Pumpkin Cat Insurance plans reimburse you for qualifying medical bills in the event of unexpected illness or injury, including care and treatment for chronic conditions, such as FIV.

One caveat: if your cat was diagnosed with FIV before your policy went into effect, any care related to FIV is unlikely to be covered. In this case, FIV is considered a pre-existing condition.

If one of my cats is diagnosed with FIV, does that mean all my cats probably have it?

No, not necessarily. FIV virus spreads primarily through cat bites. Rarely does it spread through shared contact with food bowls, litter boxes, or other surfaces. However, if one of your cats is diagnosed with FIV, you should separate the infected cat from the others and have the rest of your cats tested for the virus.

The only way to know if a cat is infected is to get them tested at a vet’s office.

Can my cat infect me with FIV?

No, you can rest assured that you and the rest of your human family are not at any risk of contracting FIV from your feline friend. Only cats can contract FIV.

Did you know

  • In North America, the infection rate for FIV is 2.5-5%.
  • FIV is often commonly confused with a fellow retrovirus, feline leukemia virus (FELV). Both FIV and FELV can cause cats to develop other illnesses, but they are distinct conditions with different causes.
  • Many cats live with FIV asymptomatically for years before they are diagnosed with the virus.
  • Pumpkin Pet Insurance plans cover 90% of eligible vet visits, helping you provide your cat with the best possible care if accidents and illnesses arise. Fetch a free quote today!

Caitlin McQuade

Caitlin is a writer and the proud roommate of an adorable and elusive cat named Olive.
Back to Top Back to Top