Feline AIDS

by
Jerry Williams, DVM
Cat Clinic
314-991-3131, Creve Coeur, Missouri

In 1986 in Northern California a disease that was causing illness and death in cats was found to be caused by a virus similar to HIV, or the AIDS virus found in humans. Since then, much research has been done on this virus and the disease it causes. To date scientists have not been successful in formulating a vaccine to prevent this infection in cats. There has also been little success in finding methods to treat those cats that have the disease, but we DO know enough about the disease to safeguard our pets from this fatal disorder.

Because of its similarity to the HIV virus, it was named FIV (feline immunodeficiency virus), and the disease it induces is known as FAIDS (feline acquired immune deficiency syndrome). The virus is classified in the same group of viruses as the HIV virus, but it is not identical. The HIV virus does not infect cats, and likewise the FIV virus does not infect humans. There is no danger that a person could catch AIDS from a cat or vice versa.

There is now a reliable blood test which your veterinarian can perform on your cat to see if it is infected with FIV. As in people, we refer to a cat who tests positive as being "FIV positive" but that cat does not necessarily yet have FAIDS, and may not become sick for months or years or in some cases not at all. When a cat does develop illness, the body’s natural defense against disease is broken down. The cat is then susceptible to a great variety of infections, cancers, etc. No one specific symptom is typical. It might be a sickly cat who is not recovering promptly from an illness, or has a chronic illness such as infected teeth or gums, frequent diarrhea or discharge from the nose or eyes. While we do our best to control other infections these cats may acquire, we cannot cure them of the FIV infection, and it is usually fatal.

The FIV virus affects only cats, so the risk for any cat of catching the virus comes through contact with another cat who is infected. The virus does not survive outside the cat’s body, so it is not blown through the air or carried on a person’s hands or clothing from cat to cat. An indoor cat that does not come in contact with other cats would be at no risk of catching the virus. Cats that are allowed to roam outdoors and may encounter stray cats have to be considered at risk to catch FIV. Studies have shown that the infection is worldwide, and in every area of the United States where stray cats have been tested the infection is present in a certain percentage of those cats. Because cats can live for months or even years while infected, they can transmit the infection to other cats.

Many studies are currently investigating exactly how FIV is transmitted cat to cat. The most common method of transmission is through a bite wound inflicted by an infected cat. In this case the virus in its saliva enters the blood stream of the bite victim. Bite wounds, however, are not the only method of transmission and virus-to-blood contact is not always necessary. FIV infected mothers can transmit the virus to their offspring but not in utero. The transmission to offspring probably takes place during nursing, and experts feel the majority of kittens nursing FIV positive mothers don’t get the disease. It is still unknown whether transmission takes place during mating, but since biting can be part of the mating ritual, we have to assume it could. Experimentally scientists have been able to infect cats by giving the virus orally. We don’t know, however, in the natural setting of mutual grooming, sharing food bowls, etc., how often this occurs. It appears that in a setting where one cat in a house is FIV positive and has non-biting contact with other cats, those cats have a low probability of becoming infected.

The blood test that veterinarians do to detect FIV is a test not for the virus itself, but for antibodies to the virus that have formed in the cat’s system. This is the same as an HIV test in a person in that it assumes that antibodies form only when you have become infected with the virus, and once you become infected you remain so for life. Therefore, a positive test for cat antibodies to the FIV virus would prove that the cat is infected. However, there are two situations which confuse this issue.
One is the kitten born to an FIV positive mother. Antibodies from the mother’s blood stream are passed in the milk to the kittens and for a few weeks the mother’s antibodies may be detectable if a blood test is done on the kitten, even though the kitten is not infected. So a positive FIV test in a young kitten must be interpreted carefully. A negative test must be interpreted carefully in any cat that was recently exposed. From the time a cat becomes infected with the virus to the time that enough antibodies have built up to cause a positive blood test takes a few weeks. So for the first few weeks an infected cat will have a negative test. In both of the above situations, the confusion can be cleared up by repeating the blood test several weeks later.

Even though we cannot cure FAIDS or vaccinate cats to prevent FIV infections, we do recommend the following steps to ensure that your cats remain FIV free:

	Take any new kitten or cat that you obtain to your vet before bringing it into your home. Be sure that the examination and testing done that day includes the FIV blood test.
	Even the most timid house cat may be inclined to fight to defend its territory when a stray cat comes around, and some stray cats carry FIV. Keep your cats indoors, or allow it outdoors ONLY under constant supervision.
	Be sure to keep your cat current on its vaccinations so your veterinarian can look for early signs of illness during the annual physical, and can offer advice on preventive health care.

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