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Information Sheet
Feline Immmunodeficiency (FIV)
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Table of Contents

What is FIV?
How is FIV Diagnosed?
What is the prognosis for cats with FIV?
Prevention of FIV
Overview of diagnostic testing for Feline Immunodeficiency virus (FIV)


What is FIV?

FIV, or Feline immunodeficiency virus, is a disease of cats that is quite similar to human HIV/AIDS. Like a person with HIV, a cat can be infected with FIV and enjoy good quality of life for quite some time before developing full blown disease. There is no cure for FIV, and cats with this disease are vulnerable to a number of secondary infections due to a suppressed immune system. Ultimately, this is a fatal disease.

Who gets FIV?

Although some wild cats can get FIV, there is no evidence that this disease is transmissible to any other species besides felines. FIV infected cats do not pose a risk for HIV infection in humans. Although it can affect cats of any age or sex, this disease is most commonly seen in intact adult male cats.

How is FIV spread?

Like HIV virus, FIV is not very readily spread. The main route of transmission is through bites. It is rarely spread through casual contact, and cats may cohabitate for years without transmitting the disease. However, bites are relatively likely to occur when a cat is newly introduced into a group. Introduction of an FIV positive cat to a household with FIV negative cats (or vice versa) therefore poses a moderate risk of disease transmission. Individually housed infected cats in a shelter do not pose an infectious risk to the shelter population.

Although transmission to kittens at or near the time of birth has been experimentally reported, in nature this appears to be extremely uncommon. Kittens born to FIV positive mothers are at low risk for infection, although they may initially test positive due to the presence of maternal antibodies.

FIV is not very durable in the environment. It is inactivated by most commonly used disinfectants. It can survive for up to 48 hours in a moist environment at room temperature.


How is FIV Diagnosed?

Blood tests are available for screening for FIV in-house or at most labs. The most commonly used test is the ELISA test, which looks for viral antibodies in the blood. It is imperative to follow the instructions for whatever test is used exactly, as the consequences of both a false positive and a false negative test are potentially severe. Staff members performing the test should be trained and periodically evaluated.

How accurate is the test?

The blood test is quite accurate, but false positives and occasionally false negatives do occur. In healthy, low-risk populations FIV is quite uncommon, and this leads to an increase in the relative number of false positive results. The blood test may also falsely identify recently infected cats as negative. To be absolutely certain, cats must be tested 1-3 months after their last known exposure.The test can not be accurately interpreted in young kittens.

There is currently no test available to distinguish between infected cats and cats that have been vaccinated for FIV.

What additional tests are available?

If resources allow, cats testing positive by the ELISA test should be retested by sending the appropriate sample to a laboratory for IFA or western blot analysis. In high-volume shelters, holding cats for retesting may not always be practical. At the very least, the ELISA test should be repeated to ensure that correct technique was used.

Strategies for FIV testing

Maternal antibodies may interfere with FIV testing in kittens. The literature is in disagreement as to when FIV screening may be performed: maternal antibody interference can rarely occur up to 4 months but has disappeared by 6 months. As mentioned, even in adult cats infection may take up to 1-3 months to develop, so a final test should be performed 3 months after the last known exposure to be absolutely certain. Samples should be tested individually, pooling samples significantly decreases test accuracy. Depending on agency resources and priorities, FIV testing may be performed at various points:

  • All cats over 4-6 months old
  • Upon admission
  • Prior to being placed for adoption; This strategy is most practical for shelters that rarely euthanize adoptable cats.
  • At the time of adoption; This can be offered as a service with or without a fee May be more practical than testing all cats in shelters where significant numbers of cats are euthanized rather than adopted. This approach risks heartache when adopters and staff have grown attached to the cat.
  • Prior to placement in group housing;t his is a must for shelters that mix cats from different litters in group housing rooms. Prior to investment such as foster care, treatment for URI, spay/neuter surgery; This is always ideal, but especially important in high risk groups (adult intact males) and populations where FIV is relatively common

What is the prognosis for cats with FIV?

Cats with FIV can live for a number of years without symptoms. However, most infected cats will develop “feline AIDS related complex” by the time they are 3-6 years old, developing a number of secondary conditions such as severe oral disease and various infectious conditions. Most FIV positive cats go on to develop full blown AIDS by the time they are 6-8 years old, and die soon after. Cats that are showing clinical signs at the time of diagnosis will likely die much sooner than those that are healthy at the time of diagnosis. Treatment consists of good nourishment, protection from stress and infectious disease, and management of secondary conditions. There is no cure for FIV infection, though the efficacy of various antiviral agents in treating the disease is an area of active research.


Prevention of FIV

Testing and removal or isolation of FIV infected cats has been an important part of reducing the overall frequency of this disease. If FIV positive cats are to be maintained in shelters, the following precautions should be taken:

  • Cats should be housed individually.
  • FIV positive status should be noted on the cage and on paperwork.
  • For their own protection, FIV infected cats should be housed well away from kittens or sick cats, which are especially likely to transmit disease to these cats with weakened immune systems.

If placed for adoption or rescue, cats should be adopted only to households where the cat can be kept strictly indoors for life and isolated from all FIV negative cats. Rescue households that focus on FIV positive cats and have many such cats should be monitored carefully and have a well developed health care program, as infectious diseases in addition to FIV can quickly get out of control in such a setting.

What about vaccination?

There is a vaccine available for FIV, although it is not 100% effective in preventing infection. FIV vaccinated cats will test positive for FIV on all currently available tests. Therefore, permanent identification of vaccinated cats such as tattooing and/or microchip is vital. Because FIV is not very readily spread, the routine use of FIV vaccination in a shelter is rarely indicated. Rather, the new owner and their veterinarian should decide whether the vaccine is appropriate for the individual circumstances of the cat.

FIV attacks a cat's immune system causing feline AIDS. It is estimated that between 2 and 25 percent of the global domestic cat population is infected with the virus. FIV is primarily transmitted from cat to cat through biting. In March of 2002 the USDA approved the use of an FIV vaccine developed by Dr. Janet Yamamoto at the University of Florida and manufactured by Fort Dodge under the brand name Fel-O-Vax. The efficacy rate of the vaccine has been reported to be 67-84%.

Currently available antibody-based FIV diagnostic tests (e.g., SNAP® Feline Combo, PetChek® FIV Ab plates, and Western blot) available in the United States and Europe cannot distinguish cats vaccinated with Fel-O-Vax® FIV from FIV-infected cats or from cats that are both vaccinated and infected. As PCR technology becomes more readily accessible as a diagnostic tool for veterinarians, and after more information on the sensitivity and specificity of such an assay is obtained, it MAY be possible in the future to distinguish a FIV vaccinated cat from one that is infected with FIV. However, due to funding constraints routine use of PCR testing in shelters is still at best many years away.

Many shelters across the United States routinely euthanize cats that test positive for FIV after their mandatory holding period. At this time the shelter medicine program recommends that only owners of "at risk cats" (indoor/outdoor or outdoor only) consider vaccinating their cats for FIV, and if vaccination is elected, it is imperative that tattooing or microchipping be performed at the same time. Having the means to quickly identify the owner of a stray cat entering a shelter with a positive FIV status can mean the difference between life and death.

*There is no indications that cats can spread FIV to people or that cats can be infected by HIV.

Other Useful Sites about FIV

Shelter Medicine Vaccine Information Site
Journal of the American Veterinary Medical Association
American Association of Feline Practitioners stance on FIV vaccination
Cornell Feline Health Center FIV information page
The Vaccine Site for Dogs & Cats