COVID-19 Information Center

FIV Vaccine

Date Published: 03/05/2012
Date Reviewed/Revised: 06/11/2019

As of 2017, the Fort Dodge/Boehringer Ingelheim vaccine was no longer marketed for the U.S. and Canada

If you are like most of the cat-owning community, you may have a vague familiarity with the feline immunodeficiency virus (FIV) but are unclear on the details. You may not even be sure about the difference between the FIV virus and the feline leukemia virus (FeLV) and you rely on your veterinarian to tell you what you need to know.

Local feral cat sterilization programs commonly involve removing the tip of an ear to designate a cat as neutered. Photo by MarVistaVet.

Fortunately, for most cat owners the FIV virus has been an academic matter. A new kitten receives a screening test usually for both FIV and FeLV, and cats are often re-tested when they are ill, but since most of our feline patients live their entire lives indoors, the FIV virus is not of much concern.

For outdoor cats, it is a whole other story. The FIV virus, or feline immunodeficiency virus, is spread by bite wounds between cats. Adult cats, rather than kittens, are at risk and the American Association of Feline Practitioners recommends that outdoor cats be tested annually for this virus and as well as for the feline leukemia virus (FeLV) regardless of their vaccination status.

Like HIV, FIV can live in its host’s body for years before leading to a life-threatening AIDS situation. Ultimately, FIV is suppressive to the immune system and predisposes the cat to numerous opportunistic infections and even cancers.

In August 2002, Fort Dodge Animal Health (now part of Boehringer Ingelheim) released a vaccine for FIV and promoted it heavily. Some veterinarians have looked at this vaccine which, on the surface, seems like a good idea for outdoor cats or cats living with FIV positive housemate cats. Some veterinarians have chosen not to use this vaccine at least until more information is available.

Some features of the product that leave some veterinarians with reservations are:

  • There are five strains of FIV virus, called Clades. The vaccine was made using Clades A and D and tested using Clade A. Clade B, for example, is a common strain in most regions of the U.S. It turns out the response to the vaccine has been variable between different Clades and there is a great deal (up to 15%) of genetic variability even within the same Clade. The vaccine might not be effective at all against the Clade that is most common in certain regions. This means that a pet owner might wrongly believe they were protecting their cat fully against the FIV virus with this vaccine.

  • The FIV vaccine is an adjuvanted vaccine. An adjuvant is an additive used with killed vaccines to improve their ability to stimulate the immune system. Unfortunately, adjuvanted vaccines have been implicated in the development of certain tumors in cats.

  • Vaccinated cats will test positive on all current methods of testing for the FIV virus. This means it will no longer be possible to distinguish vaccinated cats from truly infected cats. The vaccine is advertised at protecting 82% of cats, which means 18% can still be infected. This is nearly a one-in-five chance of unknowingly having an infected cat.

The American Association of Feline Practitioners considers this a non-core vaccine

See the American Association of Feline Practitioners Fact Sheet on FIV.

FIV infection is preventable by keeping cats indoors and preventing cat fights.