Feline AIDs and Your Cat

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What You Should Know About FIV, the Feline Immunodeficiency Virus

Feline immunodeficiency virus (FIV), also known as feline acquired immunodeficiency virus (Feline AIDs), is a virus spread between cats. FIV is transmitted by saliva (spit) or blood from an infected cat to a healthy cat. This almost always happens through bite wounds and fighting. Transmission from mother to kittens can also happen but is rare. Transmission among household cats can also happen but is uncommon unless due to fighting. Humans cannot become infected with feline AIDs.


The virus attacks the immune system, which is the part of the body that prevents and fights infections. Initially, an infected cat may show general symptoms of sickness such as fever or laying around, although sometimes infected cats show no symptoms.

Over time, the virus prevents the immune system from working properly. A cat may show no symptoms at all for many years until he develops other illnesses. Because the virus prevents the immune system from working correctly, illnesses like colds and skin infections are difficult to heal from and may become severe or life threatening very quickly.


The virus can also cause cancer within the immune system, such as lymphoma or leukemia. Again, this may take a while to develop. Once cancer symptoms occur, such as loss of energy, paleness, trouble breathing, poor appetite, or bruising, cats can succumb to the disease very quickly, even with treatment. Fortunately, tests exist that can diagnose FIV infection. Certain situations may lead to a negative test when a cat actually has the virus, such as if he or she only recently became infected. Kittens will sometimes test positive for the virus if their mother had FIV because of the mother’s antibodies in their bloodstreams. Over time, these antibodies will be replaced by the kitten’s own immune system cells and they will likely test negative at that time (somewhere between three months and six months of age). Kittens who are negative when retested were never truly FIV positive and should have no future ill effects. FIV tests may also be positive if a cat was ever vaccinated for FIV.


If your pet is diagnosed with feline AIDS, watch him or her very closely for signs of illness. Treatment options for the virus itself are limited and not capable of curing FIV infection. However, the sooner new health problems such as dental disease, upper respiratory tract infections, or skin issues are discovered and treated, the better your cat’s chance of healing and staying healthy. Call your vet immediately if you have any concerns or questions about how your cat is doing. Have your cat checked out at least twice a year so your vet can pick up on any new symptoms or physical changes.

Although infection among household cats is rare unless they fight, test your other cats yearly to be safe. If your cats fight amongst themselves, they need to be separated to prevent infecting each other. It is probably a good idea to feed them and provide their water separately if possible. FIV positive cats should not be allowed outside because they can infect other cats if they bite them or are bitten.

The FIV Vaccine

A vaccine exists but does not work against all subtypes of FIV. Scientific study results vary on how effective the vaccine is against the subtypes for which it is made. In other words, overall, the vaccine is not very effective. To make it even less appealing, the fact that it will cause positive test results means that any cat who has received the vaccine could be positive for the virus and we would not be able to tell.

Feline AIDs is a serious disorder than can cause severe illness and/or cancer. The good news is that infecting other cats is rare unless the FIV positive cat is fighting or being fought. In addition to that, FIV-positive cats can live for many years with the virus before showing symptoms. If you know your cat has developed FIV, making a few changes at home and keeping him as healthy as you can through frequent veterinary visits and check-ups will help him live a good quality life.