What is FIV?

FIV is the acronym for Feline Immunodeficiency Virus. It affects about 2.5% of cats across the globe. FIV should not be confused with FeLV (Feline Leukemia Virus) or FIP (Feline Infectious Peritonitis). FIV is related to its human variant (HIV), but FIV is not infectious to humans.

FIV is a virus with a long incubation time (lentivirus). This means that a cat can live for many years being infected with FIV without showing any symptoms. The virus prefers to live in white blood cells, leading those to lose their function. While the virus replicates, more and more white blood cells are affected, deteriorating the general immune system of the affected cat.

How does FIV progress?
Because FIV impacts the cat’s immune system, (s)he gets more susceptible to all kinds of infections. The time between initial infection and first symptoms of disease can be quite prolonged. Only 5% of cats infected with FIV eventually enters the FAIDS stage.

Different stages of the infection come with different symptoms:

First stage: acute

The first stage starts shortly after the initial infection. During this stage, you will notice that your cat is not feeling well, is feverish and/or has diarrhea. Often, the lymph nodes in the neck are enlarged. This stage often passes without the owner noticing, as its symptoms resemble that of any viral infection.

Second stage: latent

The duration of the latent stage varies from one cat to another: from a couple of months to several years. During this stage, the virus embeds itself into the cat’s white blood cells, where it remains present throughout the cat’s lifespan. The presence of the virus inside the white blood cells in essence does not cause major problems to the cat host.
Note: as soon as the white blood cells replicate, for example as a natural response to a viral infection, the FIV virus embedded in those cells replicates along with it. Therefore, the most important precaution to take during this stage of the disease is to keep the cat indoors, sheltered from circulating pathogens as much as possible.

Third stage: chronic

The third stage is characterized by vague symptoms such as fever, reduced appetite, weight loss and/or enlarged lymph nodes.

Fourth stage: FAIDS-related complex

In the fourth stage, the cat begins to develop several infections (on top of the symptoms mentioned under stage 3): gingivitis, stomatitis, enteritis, rhinitis, inflammation of the upper airways, skin, … The cat does not have a lot of energy, has reduced appetite, and is visibly struggling to beat infections. This stage can lasts months up to years, in which the cat can live comfortably if supported well.

Fifth stage: FAIDS

The fifth (and last) stage is referred to as FAIDS (feline acquired immune deficiency virus). The virus has now affected such a large part of the white blood cells that the cat loses its natural immunity completely. Eventually, the cat will die from an infection (s)he cannot overcome, no matter the amount of support offered. This stage typically lasts weeks up to months, but usually not years.

How is a cat infected?
First and foremost: FIV is NOT contagious to humans! (neither to dogs)

FIV passes from one cat to another. In 99.9% of infections, this happens through direct blood-to-blood contact. As a consequence, FIV affects mostly non-neutered males living outdoors. While male cats mostly get infected while fighting over females or food, females get infected during mating. The latter occurring far less often than the former. Also in this shelter, we have a ratio of about 9:1 male:female.

A kitten can be FIV+, but we can only be sure at the age of 6 months or older! Until kittens reach this age, they can test positive because of the presence of their mother’s antigens still circulating in their blood. 

How to care for an FIV+ cat?
Because FIV+ cats have reduced natural immunity, we recommend keeping them indoors in a stress-free environment. We recommend to reach out to a vet should any symptoms of infection occur. Generally, we see that with proper care and precautions, FIV+ cats are capable of reaching the lifespan of a healthy cat.

We recommend to weight the benefits and the disadvantages of vaccination carefully, and specifically for your cat. Vaccination is known to trigger the immune system and hence causes an increase in FIV+ viral load. This might not be worth it given that FIV+ cats living indoors are not likely to get in contact with viruses we are typically vaccinating for.