What is Feline Immunodeficiency Virus (FIV)?

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Feline immunodeficiency virus (FIV) can cause many types of illness as well as death in infected cats. However, FIV does not infect humans or other animals.

Feline immunodeficiency virus is more commonly found in male cats that are not neutered and in cats that fight with other cats. It is found less often in kittens and neutered adult cats. The virus is spread through the saliva and is usually passed to other cats by bite wounds.

In North America, about 3 to 5% of tested cats are found to be infected with FIV. In Latin America, up to 25% of tested cats are found to be infected.

How is FIV Transmitted?

Transmission most commonly happens through bite wounds. FIV virus is contained in the blood, saliva, and cerebrospinal fluid of infected cats. The virus is fragile outside the body and does not survive in the environment. FIV may be transmitted to unborn kittens if their mother is infected during pregnancy. FIV is found in cat populations worldwide.

Signs and Symptoms of FIV

A cat newly infected with FIV may show mild illness, with fever or a drop in appetite. These changes do not last more than a day or two before the cat is back to normal.

Shortly after initial FIV infection, your cat’s white blood cell count begins to decline, causing progressive impairment of your cat’s immune system. Many cats will remain without symptoms for several years. Medical signs and symptoms are usually due to secondary infections and chronic degenerative conditions. Symptoms may include:

  • Inflammation and chronic gingivitis in the mouth
  • Diarrhea
  • Fever
  • Pneumonia
  • Poor coat condition
  • Loss of appetite
  • Weight loss
  • Skin disease
  • Sinus infections
  • Neurological problems

After the early days of infection, the cat may not be sick for months or years. However, these cats can still infect other cats. Later in life, the cat’s infection may become active again, and the cat will show signs of sickness.

When the virus is active, it can weaken the immune system, leaving the cat at risk for different infections. The virus can also cause cancers in infected cats. As it can take many years for the virus to become active again, many cats infected with FIV can live long and healthy lives.


Your cat can be tested for FIV infection. There are many times in your cat’s life when your veterinarian will recommend testing for FIV and common infections, including:

  • Any time your cat is sick.
  • Your cat goes outdoors.
  • Your cat fights with other cats.


If your cat is new to the family or you adopt another cat, testing is advised before introducing the new cat to other cats in the household.

If your cat tests positive for FIV, further tests may be recommended by your veterinarian. Even if your cat’s first test result is negative, your veterinarian may still advise repeat testing in the future.


There are no vaccines available in the United States or Canada that can protect cats from FIV infection. FIV vaccines are only available in a few countries in the world.

Treatment and Management of Infected Cats

There are no treatments for FIV that will get rid of the infection. Infected cats should visit their veterinarian for regular check-ups, which will help your cat live as long as possible with good health. High-quality commercial diets are recommended, while raw food diets may cause serious infections. Your veterinarian will advise on blood testing, in addition to:


Infected pet cats should live indoors so they don’t infect other cats. Other cats in the same household should be tested for FIV as well. In some cases, cats that live together may need to be separated to avoid the spread of infection. Your veterinarian will help you determine what the best plan is for you and your cat(s).

Stress may play a role in triggering the virus to become active again. If there are other cats in your home, or a shortage of food bowls, water bowls, and litter boxes, it may cause stress because most cats do not like to share. Keeping litter boxes, and food and water bowls clean is also important.




Your veterinarian is your partner in caring for your infected cat. With regular healthcare check-ups and a low-stress life, your cat (s) infected with FIV may live happy and healthy for many years.