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Feline Immunodeficiency Virus (FIV)

Fact Sheet| Veterinarian Awareness

Quick Facts:

  • FIV is a retrovirus that compromises a cat’s immune system.
  • FIV is a feline-only virus that cannot be transmitted to humans.
  • Cats who test positive for FIV can live for many years without serious symptoms.
  • A positive FIV test result SHOULD NOT be a death sentence.
  • FIV is most often transmitted through a bite from an infected cat
  • Therefore, cats who test positive for FIV CAN live with FIV-negative cats with minimal risk of transmission as long as they do not fight to the point of biting.
  • A positive FIV test in a cat is not necessarily a diagnosis. False positives can occur.
  • We strongly recommend against testing community cats for FIV.
  • Spaying and neutering is key to preventing FIV spread by minimizing biting behavior that is the main mode of transmission.
  • More and more shelters realize FIV-positive cats are adoptable and creating lifesaving adoption programs for them.

Alley Cat Allies is committed to providing cat owners, caregivers, veterinarians, veterinary technicians, policymakers and anyone who cares for cats with the most up-to-date facts about Feline Immunodeficiency Virus (FIV). We have worked with veterinary experts and advisors for decades to develop best practices and protocols to protect cats who test positive for FIV.

FIV is a feline-only virus that cannot be transmitted to humans. It’s important to not confuse FIV with Feline Leukemia Virus (FeLV), though both are species-specific viruses that only affect cats.

Though there is no known cure, FIV is far from a death sentence. They have weaker immune systems, but cats who test positive for FIV can live fulfilling and happy lives like any other cats, and can live for many years, often without harmful symptoms.

Why is it important to understand FIV and how it is tested?

Consider this unfortunately common occurrence: A cat with no signs of health issues is brought to an animal shelter. Shelter staff conduct a routine FIV test, and the cat is found positive for FIV. As a result, the cat is killed. Though she showed no symptoms of FIV-related health problems, the test was still treated as a life-or-death matter.

This cat, and many others just like her, could have had a high quality of life in indoor homes with people or outdoors with their feline families. On top of that, the test may have been incorrect. FIV tests are not diagnoses and can be unreliable for multiple reasons.

Whether you have a cat who has tested positive for FIV, are trying to decide which tests to include for a Trap-Neuter-Return (TNR) program, or are answering questions from others on FIV, the information below will help you save lives.

What Is Feline Immunodeficiency Virus (FIV)?

Feline Immunodeficiency Virus (FIV) is a retrovirus belonging to the lentivirus subfamily. It infects the cells of a cat’s immune system and can kill, damage, or affect the cells’ normal functions. In short: It can compromise the immune system. FIV only affects cats and cannot be spread to humans or other animals.

How Is FIV Spread?

FIV is spread primarily through cats’ saliva, particularly when a cat bites deep into another cat.

FIV typically does NOT spread through cats grooming each other, sharing food and water bowls, or sharing a litter box. A cat who tests positive for FIV can live with a cat who tests negative as long as they get along and aren’t aggressive toward one another to the extent of serious (not play) biting.

It is possible, but less common, for an infected mother cat to pass FIV to her kittens before they are born or while they are nursing.

How Can FIV Transmission Be Prevented?

FIV cannot survive outside of a cat’s body in normal environments for more than a few hours. The virus is easily destroyed with soap and water.

Spaying and neutering cats helps prevent FIV transmission by minimizing biting behavior. When cats are spayed or neutered, fights (and any resulting bites) associated with mating decrease dramatically. Spaying and neutering also ends the transmission of FIV from mother cats to kittens.

It is important to know that the one existing FIV vaccine was discontinued in the United States and Canada because it is notorious for causing false positives on FIV tests.

What Happens When a Cat Is Exposed to FIV?

FIV can compromise the immune system, leaving the cat vulnerable to a variety of opportunistic diseases.

Cats continue to shed the FIV virus throughout their lives, which means it is always present in their saliva–but remember, it is very difficult for a cat to spread FIV to another cat other than through bite wounds.

FIV Stages

There are three stages to FIV:

  1. Initial infection/Acute Phase: The cat may experience a transient fever, weight loss, lack of appetite, and enlarged lymph nodes, though it can be hard for an owner or caregiver to see these signs.
  2. Asymptomatic Phase: After the initial infection, the cat may show no symptoms of FIV-related illness for many years. They can live normal feline lifespans. However, the infected cat’s immune system may become gradually more compromised, which leads to the third stage.
  3. Potential Clinical Phase: If a cat’s immune system is compromised enough by FIV, she could experience consequences of immunodeficiency. These include chronic inflammatory conditions (like stomatitis), secondary opportunistic infections (fever, anemia, dental disease, wounds that won’t heal), and cancer, kidney disease, or tumors. These secondary infections can be treated as they appear.

What are the Symptoms of FIV

Signs that a cat has FIV can include:

  • Loss of appetite
  • Weight loss
  • Poor coat condition
  • Persistent fever
  • Inflammation of the gums and mouth
  • Skin, urinary, intestinal, or upper respiratory tract infections
  • Persistent diarrhea
  • Seizures, behavior changes, and other neurological disorders
  • A variety of eye conditions

It is important to note that many of these symptoms may not be related to FIV at all.

How Does FIV Testing Work?

Usually, cats are initially tested for FIV with a point-of-care (POC) test, meaning they are tested at a veterinary clinic or shelter. This test, also called an ELISA (enzyme-linked immunosorbent assay), provides a quick diagnosis during the same visit in which the cat was tested. FIV POC tests are best run on a cat’s blood rather than saliva.

ELISA tests detect FIV-related antibodies, which can take 60 days or more to develop in a cat after initial infection. For the most conclusive results, cats should be retested 60 days after they were believed to be infectedespecially if they originally tested positive for FIV.

A positive FIV test in a cat is not necessarily a diagnosis. Further testing is often needed. An FIV-positive test does not require euthanasia unless the cat is already ill and suffering beyond treatment.

If a cat or kitten tests negative for FIV:

If the initial ELISA test is negative but you believe the cat was exposed to FIV, you can have the test redone after 60 days for a more accurate result.

If a cat or kitten tests positive for FIV:

If the initial ELISA test is positive, a more in-depth test is required to confirm the diagnosis. The veterinarian can send a sample to a laboratory, which will conduct a polymerase chain reaction (PCR) test or an immunofluorescence assay (IFA).

FIV tests can provide false positives or inconclusive results:

  • Standard tests only detect antibodies against the virus, not the virus itself. The presence of antibodies does not mean the cat is infected.
  • Positive FIV tests in kittens under 6 months of age should not be interpreted as FIV infection. Kittens are rarely infected with FIV but may test positive because FIV antibodies can be passed to them from infected mothers through nursing. For a more accurate interpretation, kittens under 6 months of age who test positive for FIV should be retested when they are between 8 and 12 months of age, when maternal antibodies have declined.
  • Current FIV tests cannot distinguish between cats who are infected with FIV, cats who were at one point vaccinated against FIV, or cats who are both infected and vaccinated. The Fel-O-Vax® FIV vaccine stimulated the production of antibodies that are indistinguishable from those that develop from natural FIV infection. Though this vaccine was discontinued in the U.S. and Canada in 2015, the American Association of Feline Practitioners (AAFP) says the antibodies it produced can persist for more than seven years in some cats. That means for several years to come, accurate testing for FIV will be complicated. Previously vaccinated cats will remain among the cat population and could also travel from locations where Fel-O-Vax is still in use to the U.S. and Canada.
  • Even without exposure to the FIV vaccine, FIV tests are not 100 percent accurate and can yield false positive results.

How Is FIV Managed?

Although there is no known cure, supportive care can improve the quality of life, health, and longevity for cats with FIV. An infected cat may live free of FIV-related symptoms for her entire lifetime. Any secondary infections can be treated as they occur.

Some recommendations for supportive care include:

  • Minimizing stress. Consider products like FELIWAY®, which mimic a cat’s natural calming pheromones.
  • Feeding ’em the good stuff. Make sure your cat is getting good nutrition and consult with a veterinarian to determine the healthiest possible food.
  • Being vigilant. Promptly taking cats to the veterinarian when they appear ill is especially important for cats with FIV. Their lowered immune systems mean they can contract other infections more easily. If you watch closely and get them immediate treatment, you can better protect them.
  • Staying up to date. Keep up with the latest information on FIV in case new treatments or diagnostic developments emerge.
  • Seeking support. Ask for help from fellow owners or caregivers caring for cats with FIV. You may have someone in your area with lots of experience and helpful advice. Try reaching out to our Feral Friends Network members near you.

What About FIV in Community Cats?

Alley Cat Allies, informed by the advice of our veterinary experts, strongly recommends against testing community cats for FIV. Studies show that FIV is present in community cats at an equally low rate as in owned cats.[1] There is no need for particular concerns about community cats, who thrive in their outdoor homes.

In addition to low rates of FIV, low likelihood of transmission between neutered adult cats, and poor viability of the virus, the cost of testing makes regular community cat FIV tests irresponsible. Plus, these costly tests can provide inconclusive results. Not only can testing needlessly endanger community cats’ lives if their results are positive, it simply isn’t worth the money spent.

Investing funds in spay and neuter programs like TNR, Shelter-Neuter-Return (SNR) and Return-To-Field (RTF) is a far better way to protect cats outdoors from FIV. You can find the details in the “How Can FIV Transmission Be Prevented?” section above

Caregivers can help community cats with FIV by providing care including:

  • Shelter or a quiet place to rest
  • Good nutrition
  • Swift veterinary services if cats ever appear ill

As of 2020, the American Association of Feline Practitioners (AAFP) Feline Retrovirus Testing and Management Guidelines are now further in line with Alley Cat Allies’ FIV recommendations.

Read for more information about selection and interpretation of FeLV and FIV tests and suggestions for FIV-positive cat care from the (AAFP).

Best Practices for Veterinarians and Animal Shelters

A cat who tests positive for FIV at a veterinary clinic or shelter should not be euthanized unless she is already ill or suffering beyond what can be treated. FIV testing should be done with a plan to help the cat if she tests positive, not to end her life.

No veterinary hospital or shelter should prohibit a cat who tests positive for FIV from leaving with her owner or caregiver. People should be allowed to take their cat regardless of test result. If a healthy community cat is brought into a veterinary clinic for spay and neuter as part of Trap-Neuter-Return (TNR), she should not be tested for FIV at all.

Alley Cat Allies recommends that adoptable cats in shelters be tested for FIV in-house only if they will be placed for adoption regardless of the result rather than “euthanized.” Shelters can also simply advise adopters to have their new cat tested for FIV at a veterinary clinic and not test in their facilities at all.

All shelters should implement programs that help find homes for adoptable cats who test positive for FIV. Many shelters already have model programs that can be used as blueprints.

Additional Resources

[1] “Prevalence of feline leukemia virus infection and serum antibodies against feline immunodeficiency virus in unowned free-roaming cats,” JAVMA, Vol 220, No. 5, March 1, 2002