Home » Pet Health » PET FIV » What Is FIV?


What Is FIV?

The Feline Immunodeficiency Virus (FIV), commonly known as Feline AIDS, is an infectious virus that attacks the cells and suppresses the immune system of a cat. The virus belongs to a family of viruses known as lentiviruses, which are slow-acting illnesses that only make themselves known over time, allowing infected cats to remain healthy for years before showing actual signs of infection. 


FIV results in the suppression of the immune system, which is responsible for the protection of cats from common infectious agents in the environment (viruses, bacteria, and so on). Once the immune system is weak enough, these same agents can cause diseases—known as an opportunistic or secondary infection. While it is a species-specific virus, it is still recommended for immunocompromised people (such as AIDS and chemo patients) to not reside with FIV-positive cats as the likelihood to acquire opportunistic infections is high.


Even with the threat of death looming over untreated cats and no known cure on the horizon just yet, an FIV-positive cat can still live a normal life for several years as long as they commit to a well-balanced diet and treatment of secondary illnesses.

Facts About The Virus

According to the International Cat Care, the virus was identified after an investigation during a disease outbreak among rescue cats in the United States. The cats showed medical signs and symptoms similar to those seen in people with AIDS, caused by infection with the human immunodeficiency virus (HIV). Despite their similarities, HIV and FIV are species-specific illnesses, meaning that HIV can only infect humans and FIV can only harm cats. There is no real danger of transmission to humans from a sick cat.


A severe bite wound from an infected cat to a healthy one is the most typical transmission method for the illness to spread from one feline to another.


The virus is always present in the saliva of an infected cat. It is transmitted to a healthy cat under the skin after a bite. Intact cats (those who have not been neutered or spayed) and cats that are allowed outside are the most vulnerable to infection. 


Due to intact animals being more violent, they are more likely to engage in conflicts and aggressive acts with other cats. The danger to cats that go outside is gradually higher than those who spend more time inside as they are more likely to encounter an intact animal (Kitten Rescue, 2018).


Many animal illnesses are spread through body fluids, which may be problematic if several animals share the same living space. Fortunately, cats who live together are unlikely to catch Feline Immunodeficiency Virus via casual touch, as cats who share a house are more likely to get along. The virus is not a genetic predisposition. However, in rare instances, it can be transferred from mother to kittens at delivery or through milk during nursing. Sharing food bowls or other personal things is also a rare way for a cat to get FIV.

Incubation Period

The Feline Immunodeficiency Virus has an incubation period that lasts for several months to even years. The virus is a lentivirus or a “slow virus”. Meaning it develops slowly over time and requires years to display symptoms. Several cats can live normally for many years before succumbing to some other medical problem even before the FIV infection causes any issue.

Physiological Changes

FIV is a virus that affects the cells of a feline’s immune system, particularly the white blood cells or lymphocytes. The virus targets and destroys white blood cells, effectively weakening the immune system and reducing the body’s ability to combat other illnesses. FIV causes a gradual decline in health and causes recurring bouts of disease with periods in between normal health.
The virus begins to multiply inside the body during the first few weeks following infection, potentially causing symptoms like mild fever and enlarged lymph nodes to show. The body will generate an immune response to combat the virus, attempting to restrict the rate of viral replication to a minimum level. This stage frequently remains undetected and unnoticed until the lymph nodes have grown significantly. Also, a cat may then go a long time without showing any signs of disease. During the next stage of the illness, after a considerable period has passed, some infected cats will experience an upsurge in viral replication. This phase usually lasts between 2-5 years following the first infection. The immune system of the cat is severely weakened by the second surge in viral replication, and symptoms might appear anywhere on the cat’s body (International Cat Care).
In the following stage of the disease, some infected cats will have an increase in virus replication after a long period of time has passed.  This time period typically ranges from 2-5 years after the initial infection.  This second increase in viral replication takes a major toll on the cat’s immune system, and symptoms can occur anywhere in a cat’s body (International Cat Care).

Survival Rate

The life expectancy of FIV-infected cats varies depending on the severity and stage of the disease. Some cats will display signs right away, while others will go years without showing symptoms. It is crucial to understand that being diagnosed with FIV does not guarantee a death sentence. Even though the disease can be deadly if the signs are untreated, an FIV positive cat can still live a long and happy life!


FIV infections are more frequent in areas where cats live in close quarters or in outdoor male cats who wander around freely. Crowded conditions often lead to catfights, which is the primary mode of transmission. On average, about 1-5% of healthy cats will be infected with FIV.


For high risk felines, such as those with weak and compromised immune systems, the prevalence could be as high as 15-20%. Infection is also more frequent in outdoor cats than indoor cats, and male cats are roughly twice as likely to contract it as female cats. Although cats of any age can be sick, the most prevalent diagnosis is in cats between 5 and 10. (International Cat Care).

Fact Vs Fiction

Myth 1: FIV is an incredibly infectious virus.

Fact: When cats are spayed or neutered, the rate of transmission drops to almost zero. FIV is only transferred by the saliva of an FIV-infected cat in a deep bite wound. Illness would not spread as long as cats do not fight aggressively.

Myth 2: Being diagnosed with FIV equals a death sentence.

Fact: FIV-positive cats can have long and happy lives! Cats can have a good quality of life and not show any symptoms for years even if they have a positive test result.

Myth 3: An FIV-positive community cat has been found. It should not be brought back to the colony.

Fact: According to Niki Cochran, program manager of Alley Cat Rescue, after being spayed and neutered, cats can be brought back out to the community if they are both thriving and healthy.

Myth 4: An FIV-positive kitten will die young.

Fact: There is a risk a kitten would not survive, but there is also a good chance the kitten will be asymptomatic (meaning it would not show any symptoms) and lead a happy and healthy life.

What Is The Link Between FIV and HIV?

A particular protein identified in the Feline Immunodeficiency Virus (FIV) is also found in the Human Immunodeficiency Virus (HIV). Both illnesses damage and impair their host’s immune systems, making the body more vulnerable to infection. Although the two viruses are species-specific, scientists can study FIV to learn more about HIV due to their similarities. Scientists believe that by knowing more about FIV, they will be able to apply what they’ve learned to treat and ultimately cure HIV (Whiteman, 2018).

Helpful Resources

Top 5 FAQs

Yes, they can live with other cats as long as the infected cats are spayed or neutered.

No. Humans cannot contract FIV since the virus is species-specific.

FIV is transmitted from an infected cat to a healthy cat through a severe bite wound. It is common in crowded environments or with intact outdoor male cats, as they tend to be more aggressive.

Not necessarily! Even though FIV-positive cats are more prone to diseases due to their weaker immune systems, some cats may not display symptoms for years. Each situation is unique. Although, some cats will require more medical attention than others.

There is much debate and disagreement about whether or not cats should be tested for FIV and FeLV if at all, given that those that test positive typically enjoy long and healthy lives. If your cat is displaying symptoms of disease or bringing a new cat into a multi-cat household, consult your veterinarian about whether or not they should be tested. Visit Alley Cat Allies for more information on the debate.

Other Frequently Asked Questions

To prevent further transmission and spread of FIV, you should keep your FIV-positive cat inside your home. However, it is becoming more widely accepted, particularly among community cats, that a cat can be released back into the community after being neutered or spayed.

Although there is currently no treatment for FIV, a positive test is not a death sentence! Consult your veterinarian about treatment choices and supportive care measures if your cat has been diagnosed with the illness.



Can FIV Be Transmitted to Dogs? Understanding FIV Transmission PET FIVPet Health

Can FIV Be Transmitted to Dogs? Understanding FIV Transmission

There are a lot of misconceptions about FIV or the …

Read More »
cat fiv PET FIVPet Health

Can Cat FIV Be Spread Through Water Bowls?

The Feline Immunodeficiency Virus, mostly known as FIV, is a …

Read More »
fiv to dogs PET FIVPet Health

How Contagious Is FIV To Dogs?

With a disease having the tag “feline” on its name, …

Read More »