Feline Immunodeficiency Virus Disease In Your Cat – FIV Feline AIDS

Ron Hines DVM PhD

Feline immunodeficiency virus is also called FIV or Feline AIDS. It is a retrovirus, a very distant relative of the human AIDS virus.

It infects only domestic and wild cats. (if it can cause disease in these larger wild felines is still debatable (ref) )The virus that causes this disease probably was around forever, but it was not recognized until 1986. It occurs all over the World. It is estimated that 2-3% of cats in the United States are infected. It is a very distant relative of the human HIV virus. Many of the symptoms we see in cats with Feline AIDS are similar to the signs seen in people with human AIDS who do not receive treatment.

Outdoor, un-neutered male cats and all cats that fight over their territory are at particularly high risk of this disease. The virus is present in the saliva of infected cats and it is primarily passed through cat bites. So indoor cats are at much less risk. Multiple-cat households are also a bit more at risk. Infected mother cats sometimes pass this disease on to their kittens. But sometimes they do not.

What Are Some Of The Signs Of FIV In My Cat?

FIV usually has three distinct stages in cats.

A few month after a cat is bitten by an infected cat, the pet will often become depressed and run a  fever . At the same time, the lymph nodes located under its skin often become enlarged.

During the second stage of the disease, the cat appears to recover. However, the virus is still there.

During the last long stage of the disease, the cat looses its normal immune system. It becomes immunosuppressed and unable to prevent infections. During this time, these cats suffer from infections of the mouth, nose, eyes, skin, lungs and intestines. Cats often become anemic during this period. These cat often loose weight and look scruffy and ill-kept. This is because they just don’t feel good. They often have strong mouth odor and oral infections that make it hard for them to eat.

These problems come and go between periods of relatively good health and correspond to periods when the cat’s white blood cell counts are very low. Stress of any kind will cause them to relapse.

How Did My Cat Become Infected?

Most cats are infected by the bite of an infected cat. Outdoor cats are very territorial. The ruling cat will bite any strange cat that wanders onto its territory. Many of these ruling cats carry the FIV virus. They are king of the block only until the virus begins to weaken them. But by then, they have passed the disease on to other cats.

Mother cats only pass the disease on to their kittens during the early stages of infection.

How Will My Veterinarian Diagnose Feline Immunodeficiency Virus Infection In My Cat?

Veterinarians have a simple in-house  test for FIV. The test is very accurate in cats over six month old and takes only a few minutes to run. Sometimes, the test is sent to an outside laboratory as part of a complete blood test.

If cost is not an issue, these tests can be run on your cat every year. However, it should definitely be run in these specific situations:

1) When you first obtain a new adult cat or kitten

2) When you add a known negative cat to a group of cats whose FIV status is unknown.

3) When your cat shows signs of unexplained illness

4) When a kitten with a positive titer reaches 6 months of age

When a cat is positive on the in-office test, a blood sample should be sent to an outside laboratory to have the results confirmed or denied by a second method called the Western Blot.

The in-office test only requires a few drops of your cat’s blood. Adult cats that test positive for FIV on this test generally remain positive throughout their lives. Immature cats often become negative for antibody over a three to five month period. These kittens never had the virus – only their mother’s antibody. A small percentage of cats will give a weakly positive, indecisive reading with the SNAP test. These cats need to have a blood sample sent out for the Western Blot test or be retested with the office test in 2 months. A drop in intensity of the reaction at that time is a good indication that the cat is recovering from the infection.

Very early in the disease, the in-office test can give false negative results. That is why cats that are known to have been exposed to FIV should be tested twice at three-month intervals to be certain they are not incubating the disease.

Is There Any Effective Treatment For FIV/ Feline AIDS?

Cat owners like you are naturally desperate for cures once they discover that their beloved pet is infected with the feline immunodeficiency virus. And there are plenty of opportunists out there willing to sell you worthless remedies. But in 2015, NIH-funded research at the veterinary college in Raleigh, North Carolina aimed at discovering effective human AIDS treatments, made major advances in our understanding of what might be necessary to develop effective treatments for cats with FIV. You can read their report here. (ref) Perhaps enhancing the cat’s interleukin-2 production may prove to be beneficial to fiv-positive pets. Merial is already experimenting with a vaccine that does just that in an attempt to increase the effectiveness of feline injection site tumors treatment when those tumors occur in cats . (ref).

One study summarizes most of the drugs that have commonly been used. (ref)


Most of the signs of sickness you see in your pet are due to it’s reduced ability to fight infection. Cats usually rebound dramatically when given appropriate antibiotics. However, this is an improvement that will not last indefinitely. It is best if the antibiotics are reserved for times of setback and not given continuously. If given continuously, they will loose their effect. But they can be given again and again when the cat’s condition warrants it.

A factor you should consider before considering long- term antibiotic therapy in your cat is the creation of a population of “super bacteria” in your pet that are immune to many antibiotics. These bacteria can spread to you or other family members. They are particularly dangerous in people with weak immune systems or chronic diseases.

Nutritional Support:

Cats with advanced FIV loose weight. So anything you can do to encourage your cat to eat is important. Because of they often have poor appetites and the intestinal problems, FIV cat also benefit from increased vitamin levels and calorie and protein-dense diets that are easily digested. These can be diets designed for cats in recovery or diets you prepare at home. If you make them at home, they need to be nutritionally balanced . You can often encourage your cat to eat by simply preparing a savory top-dressing to go on its regular food. This can be a rich broth of chicken or beef. Tuna is addictive to some cats. But you can use it as a base for the stock if that is the only way that you can tempt your pet.

Medications That Might Give A Boost To Your Cat’s Immune System:

Cats that are sick with FIV are ill because their immune system has become weak. A number of medications are sold that attempt to improve the cat’s immune system. There is no independent scientific evidence that any of them will help your cat. But they might be worth a try to gain a little bit more precious time with your pet. These include Acemannan, which is an extract of aloe vera, Immunoregulin and Interferon alpha.

Medicines Developed To Treat Human HIV:

Some veterinarians have attempted to treat their feline AIDS patients with drugs that help human AIDS patients. The most common of these is AZT (Retrovir®) and PMEA. The results have not been as good as one might hope for.  AZT can also cause toxic complications that include, anemia and liver or bone marrow damage.

Rapamycin (Sirolimus): Nothing would delight me more than to offer you an effective treatment for FIV. As you have read, I have none. But that doesn’t mean there never will be one. I recently became aware of an interesting compound called Rapamycin that appears to have anti-aging and  anti-retroviral  properties. Often, newly discovered drugs like these that seem to offer miracles, loose their luster when they are more closely examined by scientists. This appears to be one of them.

In 2006, a company called Imulan was granted a conditional license by the USDA to market a product for FLV+ and FIV in cats called Lymphocyte T-Cell Immunomodulator (LTCI). To be granted such a temporary license, a company is supposed to convince the USDA that their product is safe, and has a “reasonable” chance of turning out to be effective. It would be marvelous if this product did turn out to be effective. However the verdict is not in yet. The only article I know of on this product was written by the scientific officer of the company that sells the product – something akin to having a politician count his own ballots. The article was not published in a Journal I trust, such as JAVMA, CJVR or the BVJ and in reviewing the brief history of this journal, it is overloaded with articles touting the benefits of products produced by the various authors’ companies. Nor has this journal met the selection requirements of the National Library of Medicine (ncbi). It would be a relatively “no-brainer” experiment to supply the product free to one group of cats and not the other and see which group lived longer.

I don’t find anything wrong with the theory behind the product and perhaps it will help your cat. Given a few more years, human trials on the effectiveness of immunomodulators will become more apparent and veterinarians will have used this one enough to evaluate its true worth. That said, nothing would delight me more than that this product actually helped your cat.

These reservations apply equally well to an option European cat owners have had for a number of years that we in the US do not have, Virbagen Omega. I do not believe it is of significant value.

What Does The Future Hold For My FIV+ Cat?

FIV is the virus that causes an AIDS-like syndrome in cats; however, there can be a long asymptomatic period before show signs of illness and your veterinarian’s job is to prolong this asymptomatic period as long as we can ( The average life expectancy from the time FIV is diagnosis is 5 years) . My experience has been that the worse a cat looks when it is initially presented to me, the shorter it’s life will be.

There are sophisticated tests that help predict how much damage to the pet’s immune system has already occurred. But I see no need to run these tests on most cats with FIV. The cat’s general appearance is a better indicator of the success of treatment.

When you know that your pet is FIV-positive, you need to think about what you will do for your cat when its life is no longer pleasant. Veterinarians can help with life support and some palliative treatments. But FIP is eventually a steady slide down hill. There will come a time when you will need to make the decision to put your cat to sleep. When this time arrives, it is the greatest present you can give your feline Friend. Do not extend its life beyond what is kind and joyful. It would not want that.

Can My Cat Be Immunized Against Feline Immunodeficiency Virus To Prevent It From Catching The Disease?

Yes. Since 2002, a vaccine, Fel-O-Vax®   FIV, has been available to prevent feline immunodeficiency virus infection. The vaccine is said by the Company to be about 80% effective. However, once a cat has received this vaccine, it will test false positive for FIV. That means that your veterinarian currently has no test that would tell if your cat later caught the FIV virus – as one-in-five could. You are much safer just keeping your FIV-negative cat indoors and outdoors only on a leash in cat-safe areas. If you can not do this, then using this vaccine may be a good idea. 

A second problem is that this vaccine contains adjuvant chemicals to enhance its effectiveness. Some adjuvants are thought to be the cause of a dangerous cancer in cats, fibrosarcoma.

Cats should have a blood test before being vaccinated to be sure they do not already carry the FLV virus.

How Can I Minimize The Risk Of My Cat Being Exposed To The Feline AIDS  Virus?

This disease is one of the best reason I know of for you to keep  you cats indoors. Keeping your pet safely inside your home  eliminates the fight wounds which spread FIV and other diseases as well as the debilitating abscesses so common in cats that run loose.

Do not bring cats whose FIV status is unknown into your household if your cats are FIV virus free. It is true that it generally requires a bite to transmit the disease. But why risk that? Is it fair to your other cats? There are plenty of FIV-negative cats that are desperate for a safe new home. If you want to open an FIV cat hospice, God bless you. But do not mix your priorities or count on continuous good luck.

I would wait one or two months before bringing a negative cat into an area that was home to an FIV+ cat. It is true that the virus dies very quickly when it is outside of a cat and that the virus is killed by ordinary household bleach, drying and sunshine. But for your peace of mind and mine, I think that a month or two is not too long to wait. 

Special Care To Support Your FIV+ Cat

Your cat will now be at more risk of health problems of all kinds. So you need to keep a closer watch than you once did for minor changes in health or behavior .

Bring your pet in for a checkup more frequently. Twice a year should be sufficient if there has been no noticeable change it the pet’s health.

Weigh your cat frequently and keep a diary of its body weight. Cat’s that do not loose weight tend to be cats that are dealing well with FIV. Check its stools frequently to be sure they remain firm.

Minimize stress in your cat’s life. Your pet should not be boarded. Hire a cat sitter instead when you travel. Feed a premium diet to your pet. Avoid any activities that seem to make your cat fearful or unhappy.

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