Feline Immunodeficiency Virus (FIV) is a potentially devastating and fatal viral disease of cats. First isolated in 1986, FIV is similar to Human Immunodeficiency Virus (HIV). Infected cats can live for years with the virus without becoming ill but may eventually develop an AIDS-like syndrome. FIV is only contagious to other cats. It is not contagious to people.
Cats can transmit FIV to other cats only through deep bite wounds, not through urine, mating or casual contact. FIV has three stages of infection. They include an acute phase associated with various symptoms, which include infections, fever and lymph node (gland) enlargement. The second phase is called the subclinical phase, which lasts from months to years, during which time many cats appear healthy. The third phase is chronic infection, which is associated with deterioration of the immune function and predisposes cats to a variety of infections.
The prevalence of FIV in the cat population is unknown but it estimated to be between 1 and 15 percent. Outdoor, free-roaming cats are most at risk of developing FIV due to catfights. There is currently a quick and easy test that can be performed to determine if the cat is positive for FIV or not. It is recommended that all cats be tested for FIV as well as Feline Leukemia Virus at an early age. At-risk cats may need to be tested periodically throughout life.
Previously, the only prevention was to keep cats indoors, or just accept the risk that an outdoor cat could eventually acquire FIV. Recently, after years of research and testing, the Fort Dodge Animal Health company has developed a vaccine to help reduce the risk of becoming infected with FIV. Created from killed FIV virus, the vaccine can be given to kittens as young as 8 weeks of age.
The Feline Immunodeficiency Virus vaccine was initially tested on over 680 cats. It was found to be 84 percent protective against FIV, which means about 16 percent of vaccinated cats still developed FIV when exposed to the virus. But, without the vaccine, 90 percent of cats exposed to the virus became infected. After administering the vaccine to over 2,000 cats, the rate of adverse reactions was very low, about 1 percent. The most common reactions were pain on injection site, fever and lethargy that only lasted a short time.
All cats should be tested for FIV before being vaccinated to ensure accurate results. The vaccine will interfere with the test by showing a positive result due to the vaccine. If not tested before being vaccinated, it may be difficult to determine if the cat is actually positive for the actual virus or the tests are positive because of the vaccine.
Initial testing of the vaccine has indicated that protection after vaccination lasts for about 12 months. This means that vaccination should be repeated every year to continue to provide protection. As with any vaccine, it should only be administered to cats that are at risk. It is uncertain if the FIV vaccine will contribute to the feline vaccine sarcoma syndrome or not. Indoor only cats, especially single cat homes, will likely not be candidates for the FIV vaccine but it is best to discuss vaccination of your cat with your family veterinarian.