Understanding Feline Immunodeficiency Virus (FIV) in Cats
Featured in Houston Pet Talk, July 2024 issue
By Dr. Noaker
Feline Immunodeficiency Virus (FIV) is a condition that weakens a cat’s immune system, making them more susceptible to infections. While there is no cure for FIV, indoor cats with the virus can generally live normal life spans with proper veterinary care.
Risk and Transmission
The primary mode of transmission for FIV is through bite wounds from an infected cat. FIV does not appear to be spread through casual, non-aggressive contact, such as sharing water bowls or mutual grooming. Cats with and without FIV can safely live together when their social structure is stable (no fighting that leaves wounds).
Because FIV is transmitted through bite wounds, un-neutered male cats with outdoor access, especially those who are likely to fight with other cats, are at the greatest risk for FIV infection. There is currently no vaccine commercially available in North America to protect against FIV.
Clinical Signs
There are three phases of infection with FIV: the acute phase, the asymptomatic (or latent) phase, and the progressive phase.
The acute phase of infection generally occurs 1-3 months after infection. The virus is carried to lymph nodes, where it reproduces in the white blood cells and spreads to other lymph nodes throughout the body, resulting in temporary lymph node enlargement that is often accompanied by fever, lethargy, and lack of appetite. This phase of infection may be very mild and is often altogether overlooked or attributed to other causes of fever.
Following the acute phase, cats will enter an asymptomatic phase, which may last for months to multiple years. During this time, the virus replicates very slowly within the cells of the immune system, and cats will not show any outward signs of illness. Some cats will remain in this stage and never progress to more severe disease.
If the virus does spread through the immune system, cats will enter a progressive immunocompromised state during which secondary infections may occur. Most illnesses will not be from the FIV virus itself, but rather from secondary infections or problems with the immune system.
Diagnosis
It is important that the FIV status of all cats be determined when they are first acquired, if they become ill, and regularly if they have any risk of exposure (for example, a fight with an unknown cat).
When a cat is first infected with FIV, its immune system develops antibodies against the virus that stay in the blood for the rest of the cat's life. Your vet can perform a simple blood test that will check for these antibodies.
Kittens sometimes test positive for the virus because they are carrying their mother's antibodies. It is important to retest FIV positive kittens until they reach 6 months of age to determine if the antibodies remain, indicating a true FIV infection, or have been eliminated by the body.
Treatment and Management
Unfortunately, there is currently no definitive cure for FIV. However, it is important to remember that cats infected with FIV can live very normal, healthy lives with other household cats for many years with proper care.
Human Health Concerns
Although FIV is similar to human immunodeficiency virus (HIV) and causes a feline disease similar to acquired immune deficiency syndrome (AIDS) in humans, it is a highly species-specific virus that infects only felines. There is currently no evidence that FIV can infect or cause disease in humans.
