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  5. What are Feline Immunodeficiency Virus (FIV) and Feline Leukaemia (FeLV) and how do I protect my cat from them?

What are Feline Immunodeficiency Virus (FIV) and Feline Leukaemia (FeLV) and how do I protect my cat from them?

There are a number of feline viruses in Australia which can cause illness in cats. In addition to the three most common viruses, feline herpesvirus, feline calicivirus and feline panleukopenia (enteritis), there are two other important viruses which can cause disease – feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV).FIV is estimated to infect between 14-29% of the Australian cat population, whilst the prevalence rate for FeLV is much lower than FIV, with only 1-4% of the population estimated to be infected. Prevalence rate varies depending on the location, with the highest rate of infections for both FIV and FeLV occurring in Western Australia.

How does FIV spread?

FIV spreads throughout the body by replicating and then destroying the body’s immune cells. Symptoms of clinical FIV vary and can include weight loss, anaemia and gum inflammation (gingivitis). Often compared to Human Immunodeficiency Virus (HIV), it shares many similarities such as a long incubation period (time from exposure to infection) and a latency period (time when infected animals are not showing any symptoms of disease). However, where it differs from HIV, is in the way it is spread. FIV is primarily found in the saliva of cats, meaning the most common source of FIV exposure for cats is a deep bite from an infected cat. It is not easily spread from casual or familial contact, so an infected cat grooming a non-infected cat is very unlikely to spread the disease. Sharing feed bowls and litter trays should not pose high risk. However, cats getting into serious fights, where bites puncture the skin, are at high risk of contracting FIV.

Is FIV the same as Feline AIDS?

Although the two terms are sometimes used interchangeably, FIV is not the same as Feline AIDS. FIV can cause an AIDS-like condition, however like in HIV, AIDS (Acquired Immunodeficiency Syndrome) is the end stage of the virus which occurs after the long latency period. Feline AIDS is often an outcome of an FIV infection, however some cats may never develop feline AIDS.

My vet has told me my cat has FIV. What can I do to help?

A diagnosis of FIV is not necessarily a death sentence for cats. Prognosis depends on the age when diagnosed, whether other illnesses are present, and the capacity of the owner to minimise further risks which may exacerbate the disease. Once a cat has been diagnosed with FIV, they should be kept strictly indoors to prevent further spread of the disease and limit exposure to injuries or infections. Preventative health care is essential, and FIV cats should have annual or bi-annual health checks with a veterinarian. Good nutrition and dental care are also very important, as is a stress-free household to promote good health. If you have another cat in the household which is FIV-negative, discuss with your veterinarian about protective options such as vaccination.

How do I prevent my cat from contracting FIV?

The best way to prevent a cat from contracting FIV is to keep them indoors. As FIV is spread through deep bites, a cat kept exclusively indoors will be extremely unlikely to contract FIV. Cats most at risk of FIV (due to their propensity to fight) are male, entire (undesexed) and live mainly outside. Desexing your cat will help reduce their risk, however access to the outdoors will always increase the risk of exposure to FIV.

Should I vaccinate my cat against FIV?

There is a vaccine for FIV called Fel-O-Vax FIV®, which is offered by most veterinarians. Although this vaccination can reduce the risk of FIV transmission, it is not fully effective, with field studies showing a 56% protective rate (Westman 2016). This means that even if you get your cat vaccinated annually for FIV, if they roam outdoors, there is still a moderate risk they will become infected. Discuss with your veterinarian if FIV vaccination is appropriate for your cat and circumstances, keeping in mind that it will not entirely eliminate the risk of the disease.

What about Feline Leukaemia Virus (FeLV)?

FeLV often results in a rapid decline in health, as it causes tumours of the immune system such as lymphoma and leukaemia. Symptoms of FeLV vary and can include weight loss, enlarged lymph nodes, fever and respiratory infections. Cats infected with FeLV have poor survival rates, with an average of 2.5 years survival post-diagnosis. Also known as the ‘friendly cat’ disease, FeLV is primarily spread through prolonged contact with an infected cat, through grooming and sharing feed bowls. The virus is shed in saliva, faeces, blood, sexual fluids and urine. FeLV is primarily a concern for group housed cats such as rescues and breeders. Discuss with your veterinarian whether vaccinating your cat against FeLV is appropriate for your circumstances, and consider getting any new cats tested for FeLV before bringing them into your home.

Please note: The routine F3 vaccination does not protect against FIV or FeLV but only herpesvirus and calicivirus which primarily cause respiratory disease (cat flu) and panleukopenia which primarily causes gastrointestinal disease (feline parvo).


Westman ME (2016) Epidemiology and diagnosis of feline retroviruses (FIV and FeLV) in Australia and a trial of FIV vaccine effectiveness in the field. University of Sydney. Available from: https://ses.library.usyd.edu.au/bitstream/2123/15836/1/Mark%20Westman%20thesis%20FINAL%20SUBMISSION.pdf

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Updated on April 30, 2019
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