A Comprehensive Guide to Feline Immunodeficiency Virus

What is the feline immunodeficiency virus? Some people refer to it as the “cats’ HIV,” which partially explains the nature of the disease.

Both FIV and HIV come from the same family of viruses, called retroviruses – viruses unable to replicate independently. They must find a host cell and “trick” its DNA into replicating the virus while at the same time destroying the cell.

This is how this cunning virus attacks the infected cat’s immune system.

Key FIV Facts to Know

Before we dive into the detail of what FIV is, let’s first learn the critical facts that will help us better understand it.

1. FIV is prevalent in approximately 2.5% to 5% of cats in the United States.


Unfortunately, the prevalence increases to about 15% in cats at a higher risk. High-risk cats are generally unneutered males and live outdoors. This is because there’s a higher chance of being bitten or scratched by another infected cat.

2. About 1-5% of cats show symptoms of FIV exposure.


This percent is considerably low because there are different strains of the feline immunodeficiency virus, and not tall show symptoms or are as dangerous.

3. The feline immunodeficiency virus was discovered in 1986.


In 1986, the first signs of FIV were discovered, and a link showing similarity to human HIV was noticed, thus classifying it in the same family of viruses.

4. It can take anywhere between 2 to 6 months for your cat to develop antibodies to FIV.


Often FIV tests may come up negative after your cat has been exposed and has contracted FIV. This is because it can take up to 6 months for the cat to develop the needed antibodies, which show up on tests.

This is why it is often recommended that a test be done at least 60 days after a suspected infection.

5. As of 2015, the FIV vaccine is no longer available in the United States and Canada.


Initially, the vaccine was released for sale in the United States in 2002 and showed positive results with limited side effects. Regardless, it was taken off the US and Canada market due to concerns that it gave false-positive results in tests.

Furthermore, it was determined that indoor cats do not need the vaccine. Also, since there are so many strains of FIV, the vaccine didn’t provide complete protection against all of them, giving cat owners a false sense of comfort.

Lastly, booster shots of the vaccine have shown signs of increasing risks of Sarcoma.

FIV in Felines vs. HIV in Humans

The feline immunodeficiency virus (FIV) discovery dates back to 1986 after scientists investigated the condition of a group of cats that were feeling unwell and had severe symptoms related to minor infections – infections that other cats seemed to recover from quickly. 

They found similarities with another virus that was being investigated at the time (that is, HIV – human immunodeficiency virus). This is the rationale behind how the FIV virus got its name.

However, there are many differences between the two viruses. For example, they are not transmitted in the same way and do not share the same number of variations.

Scientifically Beneficial Similarities

However, their numerous similarities imply that any valuable piece of information being discovered regarding one of the two viruses can be applied to the exploration of the other.

This kind of reciprocity between cat AIDS and human AIDS provides the scientists with a closer insight into both conditions simultaneously.

Therefore, the research on finding a cure for both conditions is significantly accelerated. Finally, both viruses are species-specific – HIV can never infect a cat, and a human cannot get infected with FIV.

This is probably the most crucial fact about the disease that many cat owners aren’t aware of, which unfortunately often causes them to abandon their pets.

FIV Transmission 

The primary means of transmission is through bite wounds, which are most likely to happen to male cats who haven’t been neutered and tend to wander around fighting with other cats. FIV infection spreading among cats through casual contact is believed to be impossible.

However, it can be transmitted from mother cats to kittens, either while giving birth or nursing.

Multi-Cat Households and FIV

The virus is present in cerebrospinal fluid, blood, and saliva. Still, it does not survive outside the body for a long time. This is why FIV-positive cats can live with healthy cats without putting their well-being at risk.  

Some people think they should wait for a certain period before bringing a new cat into a home where a cat with FIV lived. However, there is no need for that – as stated, the virus cannot survive on its own for long.

Besides, any responsible owner will take good care of their household hygiene, so there are no reasons to worry.

FIV Symptoms in Cats

FIV is slow-progressing, so it can take years before the virus causes any symptoms. Due to this, cats with FIV tend to reach their normal life expectancy. However, you should still be able to recognize the problem despite the inert nature of the virus – and here’s now.

Earliest Signs

In the earliest stages of the infection, the virus reaches the nearby lymph nodes, where it replicates inside T-lymphocytes (a type of white blood cell).

Afterward, the virus is carried to the rest of the lymph nodes, after which they are temporarily enlarged (a fever usually accompanies this). 

Since the extent of the enlargement might vary, feline HIV might go unnoticed during this stage (in some cats, they don’t get significantly larger).

However, a cat affected by FIV will either experience the gradual deterioration of its health or periods of illness interchanging with healthy periods. 

Commonly Observed Symptoms

Generally, there are several symptoms characteristic of FIV in cats:

  • Rough fur
  • Recurrent fever
  • Poor appetite
  • Gingivitis
  • Stomatitis 
  • Persistent fever
  • Loss of appetite

Various chronic infections affect different organs such as the eyes, skin, bladder, respiratory tract, etc.

Also, it is not uncommon for a cat to experience behavioral changes and seizures since FIV also causes neurological problems. What is also characteristic of feline AIDS is progressive weight loss.

Diagnosing FIV

For diagnosis, blood samples are taken and examined using various techniques. However, enough time has to pass before a host organism has had sufficient time to initiate an immune response.

In other words, antibodies most certainly won’t be detected immediately after a cat has been infected with the virus.

The Accuracy of FIV Testing

While tests for FIV in cats are usually accurate, a possibility of a false positive result does exist. False-negative results are also possible, especially in cats who have been infected recently.

Also, note that FIV tests cannot make a difference between FIV-infected cats and those vaccinated against FIV, so this is yet another example of a false positive FIV test.

Understanding FeLV/FIV Differences

FIV is less severe than FeLV. FIV and FeLV (standing for feline leukemia virus) both refer to viruses attacking the immune system.

However, FeLV is far more devastating than FIV because it typically results in cancer (usually lymphoma), leukemia, or severe bone marrow suppression. 

FIV Prognosis

The devastating outcomes such as cancer are primarily seen in young cats with FeLV. In contrast, an FIV-positive cat can live a normal lifespan – up to a decade or even more, as long as the secondary infections they might get are avoided or successfully treated.


Unlike FIV, FeLV is highly contagious for other cats. If your cat has FeLV, it should ideally be kept far away from other cats (preferably indoors), and by no means should it share food and water with other cats since FeLV can be transmitted even through casual contact.

FIV Cat Adoption

It is challenging to find a home for an FIV-positive cat since many people still lack proper information about the transmission of the disease. However, there is no reason not to adopt a cat infected with FIV. They can live as long as those without FIV.  

Unfortunately, many shelters still euthanize cats with the FIV virus, and the reason remains unknown. However, we can assume that this happens due to the name of the virus resembling “human immunodeficiency virus (HIV),” thus triggering fear in misinformed people.

The truth is that FIV is characteristic of cats alone, and adopting a cat with FIV won’t do harm to anyone in your family.

FIV Treatment and Preventive Measures

First of all, if you have a cat infected with FIV, stop the spread by sterilizing it. Also, if possible, your cat should always be kept away from potential virus sources.

However, this usually means keeping the cat indoors, which might not be practical for all the owners. Furthermore, any new cat you adopt must be tested for FeLV and FIV for obvious reasons.

The Infection Itself

Do your best to treat the symptoms promptly. The treatment of feline FIV is aimed at making the cat feel better. Provide your cat with the necessary supplements and quality food, like cooked meat. If that isn’t an option for you, quality canned food is acceptable. 

Dry food is not recommended because it leads to dehydration. Plus, all the carbohydrates are unnatural to the feline diet and put stress on your cat’s immune system, so try to exclude these.

Annual Vet Checkups

Cats with FIV require annual veterinary checkups. You might not notice the early symptoms since they’re often very subtle, but a veterinarian will know what to look for.

In between the vet appointments, always notify your vet if you notice any abdominal bloating or if your cat has persistent diarrhea. Also, regularly check your cat on your own for any suspicious lumps, bites, or scratches.

Staying Optimistic

If your cat tests positive for feline immunodeficiency virus (FIV), don’t get discouraged about the prognosis.

Scientists are persistently working on new treatments, and there may be some new discoveries that will help your cat before it develops any more severe symptoms. 

Act responsibly towards other animals as well –  keep your cat away from uninfected cats. Finally, remember that your cat will probably be as happy as any other cat with dedicated care and emotional investment.


How long do cats live with FIV?

An FIV-positive cat doesn’t need to have a shorter lifespan than any healthy cat.

While a cat with FIV is more likely to die before a cat without FIV as a result of minor secondary infections, their actual lifespan is heavily dependent on the lifestyle and how lucky the cat is when it comes to avoiding infections. 

In short, all cats’ immune systems are affected by age, and there are no rules regarding FIV in cats and life expectancy. They can most definitely live the entire lifespans of healthy cats, which is up to 15 years.

What should an FIV-positive cat avoid?

Everything that might further aggravate the effects of the virus.

Firstly, your cat should avoid any additional stress (you, as an owner, should know what it is that your cat finds stressful). Secondly, it should avoid secondary infections to keep the virus replication under control.

What does FIV do to cats?

Besides weakening their immune system, the symptoms following the FIV infection are usually not that severe for cats. Apart from the mild fever (usually lasting for several weeks) and the lymph node enlargement, cats infected with FIV will look completely normal. 

After these symptoms have withdrawn, it may take months or even years for the symptoms to recur, and in this case, the cat will probably appear lethargic, develop fever, reject the meals and lose weight.

How is FIV transmitted?

FIV transmission generally happens through a bite, but not gentle nibbles or superficial wounds. Only aggressive bites that result in deep injuries can transmit the virus from one cat to another.

You have nothing to worry about when it comes to other activities, such as playing, napping, sharing food and water bowls.   

When to put down a cat with FIV?

Cats infected with FIV can live quality lives, and unless they develop a severe and disabling illness that cannot be helped, there is no reason to euthanize them.

Some owners might think that FIV-positive felines put the rest of their pets at risk, but there is no reason to worry about that if the pets get along.

Is FIV contagious?

Yes, FIV is contagious, but only under certain circumstances. Firstly, it’s only infectious when talking about cats – you can’t get it from your pet.

Secondly, as mentioned, the transmission is not that simple. It’s not going to happen between cats that get along fine.

So if you do have more than one cat, and they aren’t aggressive towards each other, the risk of your FIV-positive kitten infecting your other healthy cats is extremely low to non-existent. 

Can feline HIV be cured?

No, but it can be highly manageable, depending on the health of a cat. For those with generally good health, the treatment is usually based on simply taking care of the cat’s diet and ensuring it gets all the required vitamins, fatty acids, and antioxidants. 

Also, it is essential to treat any minor infection on time because the immune system of an FIV-positive cat is weakened and requires a prompt reaction from the owner’s side.

Can humans catch FIV from cats?

FIV and HIV are both lentiviruses. However, humans cannot be infected by FIV, nor can cats be infected by HIV. As mentioned, FIV is transmitted primarily through aggressive, deep bites, during which the virus from the cat’s saliva enters the bloodstream of another cat.


There have been numerous misconceptions related to cat diseases such as feline AIDS, ranging from those related to its transmission to the ones regarding the dangers an infected cat can pose to other household cats.

Unfortunately, people still often believe in those misconceptions, thus contributing to the negative public perception of the disease. This decreases the chances for cats with feline immunodeficiency virus to get adopted.

Hopefully, we have made our little contribution towards a more positive image and the future improvement of the overall understanding of the disease.


  1. Like!! Really appreciate you sharing this blog post.Really thank you! Keep writing.

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