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Feline Immunodeficiency Virus (FIV)




Overview
Contributing Factors
Clinical Signs
Diagnosis
Treatment
Prognosis
Prevention

Overview

The Feline Immunodeficiency Virus (FIV), often called the Feline AIDS Virus, is an important infectious disease of the cat. It is likened to the AIDS virus which affects humans because of the similarities in the two viruses and the diseases which result. Fortunately, most viruses are species specific. This is the case with the human AIDS virus and with FIV. The AIDS virus affects only humans, and the FIV affects only cats.

Contributing Factors

The FIV is transmitted primarily through bite or puncture wounds from other cats that usually occur in fights. Other interactions of cats, such as sharing common food and water bowls or grooming each other (i.e. normal communal living among non-fighting cats), have not been shown to be significant in transmission. The virus can also be transmitted from a queen (mother cat) to her kitten(s) in the womb, or via her milk, but fortunately this is extremely rare (see below).

FIV more commonly affects male cats, presumably because they are more inclined to fight, especially if they are not neutered and /or are outdoors.

Clinical Signs

As with HIV in humans, after first contracting the Feline Immunodeficiency Virus (FIV), most cats will experience a symptom-free period which lasts for months, and in most cats, it lasts for many years. (In our experience, a number of cats will have no symptoms for ten years or more). When illness or symptoms do occur, we can see a variety of chronic illnesses varying from mild to severe. One of the most common illnesses is an infection affecting the gums of the mouth. Abscesses from fight wounds, which would normally heal within a week or two, may remain active for several months. Respiratory or other infections may linger for weeks. The cat may lose weight and go through periods of not eating well; the hair coat may become unkempt. The cat may have episodes of treatment-resistant diarrhea. Ultimately, widespread organ failure may occur, and the cat may die.

Many FIV positive cats, however, live a fairly normal life and die of unrelated causes at a very old age (even if infected as young adults). This scenario is much more likely to occur if the cat lives indoors in a stress-free environment and receives regular veterinary care.

Diagnosis

Evidence of exposure to the FIV can be detected by a simple blood test. The blood test tests for antibodies to the virus (which develop after the cat is infected with the virus). It does not test for the virus itself - there is no such test. A positive test means the cat has been exposed to the virus and will likely be infected for the remainder of its life. A negative result may mean that the cat has not been exposed.

However, false negatives can occasionally occur in a couple of circumstances:

  1. From the time of initial virus inoculation into the cat, it may take up to two months or longer for the test to turn positive. Therefore the test may be negative even though the virus is present in the cat, if the cat was recently exposed.
  2. When some cats become terminally ill with FIV, the test may again turn negative. This occurs because antibodies (immune proteins) produced against the virus become attached and bound to the large amount of virus present. Since the test detects antibodies, which are free in circulation, the test may be falsely negative. This is not the normal occurrence, but it does happen to some cats.

Conversely, false positive test results can occasionally occur in young kittens (not in adults). The vast majority of kittens under 4 months of age who test positive have not been exposed to the virus, and so are not truly "positive!" Instead, the test is detecting the immunity (antibodies) that was passed from the mother to the kitten. These antibodies may persist until the kitten is about 6 months old. Therefore, a kitten who tests positive should be retested after about 6 months of age. If the kitten remains positive, the possibility of true infection is much greater (meaning that the virus itself was transmitted in utero or through the milk, and not just antibodies; or the kitten was bitten by an FIV-infected cat). If the kitten tests negative, there is nothing to worry about (no infection existed, and mom's antibodies have worn off).

Treatment

No treatments are available to eliminate the FIV. Sometimes, the disease state can be treated, and the cat experiences a period of recovery and relatively good health. However, the virus will still be in the cat and may become active at a later date. Therefore, the long-term prognosis is guarded.

If you have a cat which tests FIV-positive but is not ill, it is not necessary to immediately euthanize the cat. As long as the cat does not fight with your other cats, transmission is not likely to occur. However, if the cat is prone to fighting or if another cat often instigates fights with the FIV cat, transmission is more likely. In fairness to your neighbors, it is absolutely recommended that an FIV-positive cat be restricted to your house. Owners of infected cats must be responsible so that the likelihood of transmission to someone else's cat is minimized. An indoor lifestyle will likely also enhance your FIV cat's chances of living a longer good quality life.

These cats must be seen regularly by their veterinarian. The cat's health must be closely guarded and any early signs of illness should be reported. Dental health is very important and should be maintained with a combination of professional cleaning, brushing, rinsing, and feeding a dental diet.

Prognosis

The long-term prognosis is potentially guarded. However many (and probably most) infected cats may experience years of good health.

Prevention

Keeping cats indoors is the only available preventive measure that can be recommended. There is a new vaccine currently available for prevention of FIV. However, because of concerns regarding its efficacy, as well as related FIV testing issues in vaccinated cats, we are not recommending routine use of this vaccine at this time.



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