Feline FIV
(Feline Immunodeficiency Virus)

Feline FIV (feline immunodeficiency virus) belongs to the same family of viruses as HIV (human immunodeficiency virus).

It produces a disease in felines similar to AIDS in humans, and is often transmitted through cat bites during fighting.

This family of viruses, known as lentiviruses (or "slow virus") is species-specific.

As the names imply, FIV is specific to cats, HIV is specific to people. These viruses are known for life-long infection, and slowly progressive diseases.

What is FIV?

Feline immunodeficiency virus, referred to as Feline FIV, or just plain FIV, is related to the feline leukemia virus (FeLV), in the sense that they are in the same retrovirus family.

It is easy to confuse the two viruses. They differ, however, in terms of physical characteristics and composition. They also differ in the way in which they cause disease in your cat.

Unless your cat is at risk, the infection rate is typically low, but varies greatly from region to region throughout the world. In the United States, approximately somewhere between 1.5 and 3 percent of otherwise healthy cats are infected with FIV.

In cats that are in a high risk group for infection, however, Feline FIV infection rates can be up to 15 percent or more.


The primary method of transmission of FIV is through bite wounds. As a result, free-roaming, aggressive male cats are the most frequently infected.

Indoor cats are much less likely to be infected. You should note that if you have a mix of indoor and outdoor cats, your indoor cats may be exposed to the same diseases as your outdoor cats. If your indoor and outdoor cats are prone to fighting, then your indoor cats could be at higher risk for FIV infection.

Although rare, feline FIV can be transmitted from an infected mother to her kittens. This usually occurs either during birth, or when the newborn kittens ingest infected milk.

Although feline FIV is said to not typically be spread through sexual contact, there is one thing to note. Cats are often very aggressive during mating, and this may result in biting.

Signs and Symptoms

Infected cats may show no obvious signs of illness or disease, and appear normal for years. As the cat's immune system breaks down, however, resistance to disease breaks down as well.

Eventually, FIV infection causes a state of immune deficiency that prevents the cat from fighting off other infections.

In the early stages of the disease, the virus begins to move into the lymph nodes, where it reproduces in white blood cells called T-lymphocytes. The virus then spreads to the other lymph nodes. This results in enlargement of the lymph nodes, and often fever. Unless the lymph nodes are greatly enlarged, this stage may go unnoticed.

The 3 Clinical Stages of FIV

  • The initial acute stage occurs around four to six weeks after infection. Symptoms during this time may include fever, swollen lymph nodes, low white cell count, or any combination of these. Most cats get through this stage without requiring treatment.

  • During the second stage the cat may appear relatively normal. This stage can last from months to years and cat parents may have no idea their cat is infected.

  • The third stage of FIV infection brings progressive destruction of the white blood cells, and immune system dysfunction. This is where the cat goes into full blown AIDS or FAIDS.

Since secondary "opportunistic" infections are responsible for many of the diseases associated with FIV, symptoms can be many and varied. With weakened immune systems, infected cats may easily become ill when exposed to disease causing organisms in the environment (e.g. viruses, bacteria, fungi, etc.).

Whereas normally healthy animals exposed to these ever present threats show little or no signs of illness, severe reactions and illness may be experienced by those cats infected with FIV.

A cat with FIV may show progressive signs of deteriorating health. In the alternative, we may see an alternating pattern of relative good health with recurring bouts with various illnesses.

Feline FIV causes a system-wide breakdown of the immune system. Signs and symptoms of FIV can appear anywhere throughout a cat's body. Frequently, the classic finding is a chronic infection of the gums, cheeks or tongue.

As in many cat illnesses, Poor coat condition is common in FIV patients. Persistent fever and a loss of appetite are commonly seen, with progressive weight loss and wasting in the latter stages of the disease process.

FIV Symptom List

  • fever
  • Inflammation of the gums (gingivitis)
  • Inflammation of the mouth (stomatitis)
  • chronic or recurring infections of the:gums, cheek, or tongueskinurinary bladderupper respiratory tract
  • persistent diarrhea
  • various eye conditions
  • loss of appetite
  • progressive weight loss
  • severe wasting in late stage
  • various kinds of cancer
  • blood diseases
  • spontaneous abortion and other reproductive failures
  • seizures, behavior changes, and other neurological disorders


Your veterinarian can run a test which detects the presence of Feline FIV antibodies in your cat's blood. Unless it is a false-positive, positive test result for your cat means that she is infected with FIV.

False-positive results may occur in some cases. For this reason, veterinarians recommend that positive results be confirmed using a test with a different format. While this may add to your distress during this difficult time, it is better to know for sure.

Kittens born to FIV positive mothers may test positive for FIV antibodies for several months after birth, even though they are not actually infected FIV. For this reason, kittens with positive test results should be retested at 60-day intervals until they are at least six months old.

In most cases, if your cat tests negative, this translates to non-infection. It should be noted, however, that it takes eight to 12 weeks after infection (sometimes longer) before antibodies can be accurately detected.

Therefore, if there is reason to suspect exposure to an FIV infected cat, your cat should be retested a minimum of 60 days after her most recent exposure. In other words, don't trust the first negative test result!

It is possible, although rare, that cats in the later stages of FIV infection may test negative. This is because their immune systems are not strong enough to produce enough antibodies to trigger a positive test result.

Treatment and Management

Since there is no available drug that will kill the virus, there is no cure for the disease. An infected cat is infected for life. Treatment, therefore, is more along the lines of prevention and disease management, and is focused on keeping the immune system as strong as possible.

The immune system breakdown occurs over a long period of time, and cats can appear healthy for several years after being positively diagnosed. FIV positive cats should be given a detailed examination by a veterinarian at least every 6 months for evidence of deterioration.

Your veterinarian will give special emphasis to the most commonly affected areas - the gums, eyes, skin, and lymph nodes. Because weight loss is often the first sign of deterioration, your cat's weight should be carefully tracked as well.

A complete blood count, serum biochemical analysis, worm check, and a urine analysis should be performed annually (some vets will prefer every 6 months).

Medication and therapies are used as needed, with treatment focusing on the organs and systems that are most affected. Antibiotics and immune stimulators are used to control infection.

Infections of the gum and mouth are treated by keeping the teeth clean and applying oral antibiotics. Good nutrition and preventive medical care are essential components of disease management.

Potentially, the use of human AIDS medications is possible, but they have greater side effects and are considered experimental. Also, their cost is too high to be used in most cases.

The Cornell Feline Health Center reports that scientific studies have failed to prove that "immunomodulator, alternative, or antiviral medications have any positive benefits on the health or longevity of healthy..." cats with Feline FIV. In other words, there is no value added to treating FIV infected cats who show no symptoms of illness.


A cat with FIV should be...

  • spayed or neutered
  • fed nutritionally complete and balanced diets (premium cat food)
  • never fed uncooked or unpasteurized food products
  • given as much care and attention as possible

All FIV positive cats need to be kept indoors to prevent transmission to other cats. In fact, all of your cats should be kept indoors to prevent exposure to FIV positive cats and other dangers.

Careful monitoring of the health and behavior of your cat is always important, but even more so for FIV-infected cats. Risks from food borne infection and parasites is high. Alert your veterinarian to any changes in your cat's health or behavior as soon as possible.

The above recommendations are from various experts, but you'll need to work with your vet to manage your cat's particular circumstances.

Prevention and Vaccination

The only certain way to protect your cat against FIV infection is to prevent her exposure to the virus. Since cat bites are the major method of transmission, keeping cats indoors dramatically reduces their chances of coming in contact with an infected cat.

If your house is infection free, then only FIV-negative cats should be adopted. An FIV vaccine has been developed. It is not, however, 100 percent effective. So, even for vaccinated pets, you must still prevent exposure.

An additional downside to the vaccine is that it may cause your cat to test positive for FIV! You should discuss the subject of vaccination with your veterinarian and make an informed decision.

Related Topics and More Information

The Long Beach Animal Hospital FIV page

Cat Health Problems

Cat Lovers Only

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