What is Feline Immunodeficiency Virus (FIV)?
FIV is a viral infection that affects cats, weakening their immune system and making them more vulnerable to other illnesses. Similar to HIV in humans, FIV doesn’t immediately cause illness but gradually compromises a cat’s ability to fight off infections. While an FIV-positive cat can live a long and relatively healthy life, extra care and attention are needed to keep them well.
Health Effects of FIV Infection:
Once infected with FIV, a cat can go through several stages. Initially, there may be mild symptoms like fever or swollen lymph nodes, which often go unnoticed. After this acute phase, the virus enters a latent stage where it hides in the body, sometimes for years, without causing obvious symptoms.
As the disease progresses, however, the cat’s immune system weakens. This makes them more susceptible to secondary infections such as respiratory infections, dental disease, skin problems, or gastrointestinal issues.
Common signs that an FIV-positive cat’s immune system is under stress include:
Chronic infections (often recurring or not healing well)
Weight loss
Lethargy or reduced activity
Poor coat condition
Inflammation in the mouth or gums (gingivitis/stomatitis)
Low red and white blood cells on blood tests
Because FIV compromises a cat’s immune system, even relatively minor infections can become serious if not treated promptly. Unfortunately, FIV positive cats also appear to be about five times more likely to develop high-grade lymphoma according to studies.
How FIV Spreads:
FIV primarily spreads through bite wounds, making outdoor, free-roaming cats—especially males that fight for territory—more vulnerable. It is not commonly transmitted through casual contact like sharing food or water bowls, grooming each other, or playing. However, mother cats can pass FIV to their kittens during birth or through their milk, though this is less common.
Preventing FIV Infection:
Prevalence: The prevalence of FIV infection in Australia is relatively high, with estimates ranging between 14-29% of cats testing positive for the virus. This is higher than many other countries.
The best way to prevent FIV infection is to keep your cat indoors, where they’re not exposed to aggressive encounters with FIV-positive cats. Neutering your cat can also help reduce fighting behaviors, further lowering the risk of transmission. If you allow your cat outside, consider creating a secure outdoor enclosure or supervised outings to minimize their exposure to unfamiliar cats. Testing new cats before introducing them to your household is important.
Australia is one of only three countries where a dual subtype FIV vaccine (Fel-O-Vax® FIV) is available. This vaccine offers protection against subtype A, which is the most common Australian subtype.
While the FIV vaccine can reduce the risk of infection, it’s important to note that it doesn't offer full protection, being about 56% effective according to studies. Due to this limited efficacy, annual testing and re-vaccination are recommended for vaccinated cats.
Additionally, once vaccinated, a cat will test positive for FIV on some routine tests, which can make future diagnosis of FIV infection complicated.
The FIV vaccine generally has a good safety profile, with typical reactions being mild, such as lethargy or soreness at the injection site. However, like all vaccines, there’s a small risk of an allergic reaction, so it’s important to monitor your cat after vaccination.
Caring for a Cat with FIV:
If your cat tests positive for FIV, it’s not a death sentence. Many FIV-positive cats live happy, healthy lives for many years with proper care. Here are some key ways to keep an FIV-positive cat healthy:
Regular vet visits: Schedule more frequent check-ups to monitor for any signs of secondary infections or health issues.
Preventative care: Stay up to date on core vaccinations (F3) and parasite prevention. Even though FIV affects the immune system, FIV-positive cats can still receive routine vaccines to protect them from other illnesses.
Diet and nutrition: Feed a balanced, high-quality diet to help support their immune system and overall health. Avoid raw diets, as these can expose an immunocompromised cat to harmful bacteria.
Limit exposure to infections: It’s important to keep an FIV-positive cat indoors or in a safe outdoor enclosure to prevent them from being exposed to other infections.
Prompt treatment of illnesses: Because FIV-positive cats are more prone to infections, it’s crucial to address any signs of illness early. Prompt veterinary treatment can help prevent complications.
While FIV is a lifelong infection, and there are currently no effective antiviral medications, with attentive care and management, cats with the virus can enjoy a high quality of life. If you suspect your cat has FIV or if they test positive, working closely with us will be key to managing their health and wellbeing.
References and further reading:
Westman ME, Coggins SJ, van Dorsselaer M, Norris JM, Squires RA, Thompson M, Malik R. Feline immunodeficiency virus (FIV) infection in domestic pet cats in Australia and New Zealand: Guidelines for diagnosis, prevention and management. Aust Vet J. 2022 Aug;100(8):345-359. doi: 10.1111/avj.13166.
Hosie, M. J., Addie, D., Belák, S., Boucraut-Baralon, C., Egberink, H., Frymus, T., ... & Horzinek, M. C. (2009). Feline immunodeficiency. ABCD guidelines on prevention and management. Journal of Feline Medicine & Surgery, 11(7), 575-584.