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  5. What are Feline Immunodeficiency Virus (FIV) and Feline Leukaemia Virus (FeLV)?

What are Feline Immunodeficiency Virus (FIV) and Feline Leukaemia Virus (FeLV)?

Feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) are retroviruses that attack the immune system, the same group of viruses as human immunodeficiency virus (HIV).

How common are FIV and FeLV?

FIV has been found to be common among companion cats in Australia aged two years or older with outdoor access; ~15% nationwide (9 to 20% depending on the location). FeLV is less common; ~2% nationwide (1 to 4% depending on the location) [1, 2].

How do FIV and FeLV spread?

FIV is mainly shed in the saliva, and fights involving a deep bite from an infected cat are the most common way it spreads between cats. FIV is not easily spread from grooming or sharing bowls and litter trays, so FIV positive individuals living happily and peaceably in a household with other cats should be a low risk if there is no fighting. Please note that each cat household should have multiple and physically separated key resources (such as feeding stations, water bowls, litter trays) – at least one for each cat and an extra. Please see Safe and Happy Cats for more information on creating a feline friendly environment.

In contrast, FeLV is shed in saliva, faeces, blood, sexual fluids and urine, and can be spread through bites, from infected mother to kittens, prolonged contact with an infected cat, grooming and sharing food bowls and litter trays.

While FIV is known as the ‘unfriendly cat disease’ and FeLV as the ‘friendly cat disease’, both viruses can be spread among cats regardless of whether they are known to fight [3].

How do FIV and FeLV affect cats?

Symptoms of FIV vary and can include weight loss, anaemia (a low number of red blood cells), and gingivitis (inflamed gums)

FeLV causes tumours of the immune system (e.g., lymphoma and leukaemia) and often results in a rapid decline in health. Symptoms of FeLV vary and can include weight loss, poor coat condition, enlarged lymph nodes, and persistent fever. Cats infected with FeLV have poor survival rates with a median survival time (i.e., half of patients still alive) of 2.5 years after diagnosis.

Is FIV the same as Feline AIDS?

At the end stage of the virus, FIV can cause an AIDS-like condition (Feline AIDS or FAIDS). FAIDS shares many similarities with HIV-AIDS in humans, such as a long incubation period (time from exposure to infection), a long latency period (time when infected animals are not showing any symptoms of disease), and serious infections due to a weakened immune system. FAIDS is often an outcome of an FIV infection. However, some FIV-positive cats may never develop FAIDS.

How do I prevent my cat from contracting FIV and FeLV?

  • Cat containment – The best way to prevent a cat from contracting FIV and FeLV is to keep them contained on your property. For more information see the ‘RSPCA Guide to Keeping Your Cat Safe and Happy at Home’.
  • Testing – Consider testing new cats before bringing them home and following possible exposure. Cats living with FIV or FeLV positive individuals should be tested annually [3].
  • Vaccination – Talk to your vet about FIV and FeLV vaccinations.

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

There is currently no cure for FIV or FeLV but depending on age at the time of diagnosis, other illnesses and how carefully cats are managed, it is possible for FIV and FeLV positive individuals to live normal lives for a period of time.

  • Confinement – FIV and FeLV positive cats should be kept confined to their owner’s property to prevent further spread of the disease and limit exposure to injuries or infections.
  • Preventative health – FIV and FeLV positive cats should see their vet for a health check at least once or twice a year. Good nutrition and dental care are also very important.
  • Minimise stress to promote good health.

For more information on FIV and FeLV see your vet.


[1] Westman ME (2016) Epidemiology and diagnosis of feline retroviruses (FIV and FeLV) in Australia and a trial of FIV vaccine effectiveness in the field. PhD Thesis

[2] Westman ME, Malik R, Norris JM (2019) Diagnosing feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) infection: an update for clinicians. Australian veterinary journal 97:47–55

[3] Levy J, Crawford C, Hartmann K, Hofmann-Lehmann R, Little S, Sundahl E, Thayer V (2008) 2008 American Association of Feline Practitioners’ feline retrovirus management guidelines. Journal of feline medicine and surgery 10:300–316

[4] Westman ME, Coggins SJ, van Dorsselaer M, Norris JM, Squires RA, Thompson M, Malik R (2022) Feline immunodeficiency virus (FIV) infection in domestic pet cats in Australia and New Zealand: Guidelines for diagnosis, prevention and management. Aust Vet J 100:345–359

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Updated on June 18, 2024
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