Feline Immunodeficiency Virus (FIV): What Cat Parents Should Know

Feline immunodeficiency virus (FIV) is one of the most common health conditions that affect domestic cats, with an estimated 2.5 to 4.4% of cats worldwide testing positive for the virus. Similar to HIV in humans, FIV is widely misunderstood. Learn how FIV affects cats, complications and potential outcomes for FIV-positive cats, and what you can do to protect your own cat’s health.

What Exactly is FIV?
FIV is known as a lentivirus , meaning it has a long incubation period of up to ten years. As the virus slowly takes over the cat’s immune system, they become vulnerable to secondary infections, cancer, and blood disorders, which can become severe and life-threatening. Typically, cats do not experience any symptoms or health complications until later in life. But some cats never develop symptoms at all, eventually passing away in old age due to unrelated causes.
FIV is not zoonotic, meaning it cannot be transmitted to humans, dogs, or other animals. It can only be transmitted between cats.

How Is FIV Transmitted Between Cats?
FIV is most commonly transmitted between cats through fighting. The virus can enter the bloodstream through a deep bite. It may be transmitted sexually, though there are no known cases of this happening. It can also be passed in utero or via nursing from a mother cat to her kittens, though this is also uncommon.
The virus does not pass through casual contact like mutual grooming and sharing water bowls. Many cat parents have mixed households made up of FIV-positive and FIV-negative cats. A 2014 research study from the School of Veterinary Medicine at Purdue University showed that FIV-positive cats in mixed households did not spread the virus to their FIV-negative housemates. Kittens of FIV-positive queens, too, maintained their negative status even after weeks of nursing.
Over 75% of FIV-positive cats are male. They’re typically unneutered and have been allowed to roam, where they will likely have contracted the disease in a fight. A vaccine for FIV exists, but it is not widely available. The best way to protect cats is to keep them indoors, and spay and neuter to help curb roaming, fighting, and aggression.

How is FIV Diagnosed in Cats?
After the virus enters the cat’s bloodstream, it takes at least eight weeks for the body to create a detectable level of antibodies.
FIV is diagnosed with a blood test that can detect FIV antibodies. However, false positives are common. A cat that’s FIV-negative can get a false positive test if they have antibodies, which can be passed from their mother or gained through a vaccine.
Additional testing, which can pick up on proteins or DNA, can be used to confirm a positive test in a healthy cat that may have received a false positive. Kittens of FIV-positive queens often re-test negative months after they’re weaned, when they’re no longer receiving their mother’s antibodies.

Prognosis and Treatment for FIV-positive Cats
Unfortunately, there is no cure for FIV in cats. There is no way to predict if or when a cat will have complications.
One of the most significant health concerns for FIV-positive cats is their increased susceptibility to infection. Infections of the urinary tract, skin, upper respiratory tract, teeth and gums, and eyes can become recurrent or may be harder to treat. FIV-positive cats should see their veterinarian every six months and as soon as they have any potential symptoms of an infection to ensure that they’re treated as early as possible.
End-stage FIV tends to manifest as unexplained weight loss, seizures, loss of appetite, diarrhea, and vomiting. Ultimately, cats with FIV may pass away from cancer, blood disorders, neurological disorders, and infections that resist treatment.
However, many cats survive well into their senior years and succumb to an unrelated illness before ever showing symptoms of FIV. Though this virus does pose a serious health risk for domestic cats, it is not a death sentence, and it does not have to stop a cat from having a long, happy life.