The Cat Doctor Veterinary Hospital and Hotel

I Didn’t Know Cats Can Get AIDS

By: Alexis Higdon, DVM

A very high percentage of new clients we see here at The Cat Doctor are amazed when we ask them if their cat has been tested for Feline Immunodeficiency Virus (FIV). Since spring is a time for kittens as well as breeding and fighting among adult cats I thought it was time to introduce the subject of this dangerous virus to the uneducated and update those in the know. The following is part 1 of a 2 part series on FIV.

In 1986, cats in a northern California cattery were suffering from persistent upper respiratory infections, chronic diarrhea, and severe forms of dental disease. No antibiotics, diets, supplements or other medications given to the group of cats seemed to help. At the time, Feline Leukemia Virus (FeLV) was typically blamed for these symptoms, which suggested a faulty immune system. Their veterinarian tested the cats multiple times for FeLV, but each time, they tested negative.

Finally, after exhausting standard methods of diagnosing this strange malady, the frustrated veterinarian placed a call for help to the University of California School of Veterinary Medicine. Virologists Drs. Neils Pedersen and Janet Yamamoto thought the symptoms in the affected cats sounded strikingly similar to those in people infected with the recently discovered Human Immunodeficiency Virus (HIV). The doctors ran special diagnostic tests and isolated a powerful, new virus. The new virus matched all the criteria of HIV. As a result, they named it the Feline Immunodeficiency Virus (FIV) and placed it in the same viral family as its human counterpart.

Over the past twenty years, we have acquired vast amounts of information about FIV. We know it cannot bet spread from cat to humans, dogs or any other species. We also know it is spread from cat to cat primarily through bite wounds, rarely from breeding or from mother cat to kitten and not at all through casual contact. Spread from an infected to uninfected cat within a non-fighting household is considered low risk. About 1-3% of all cats, and up to 14% of sick cats in the United States are infected. The most commonly infected cat is a fighting, roaming male. Although a newly infected cat may, for a very short period of time, run a fever, have swollen lymph nodes, anemia or diarrhea, the symptoms will resolve and the cat will appear normal for years and in most cases, the rest of his life. There are five known subtypes (variations in the virus) with two of them being most prevalent in the United States. The virus infects and kills certain critically important immune system cells, namely the T-lymphocytes.

If FIV does progress in a cat’s body, we generally see one of two signs: waxing and waning periods of illness and health, or a gradual, persistent deterioration in health resulting in illnesses that are not controllable or curable. Symptoms of active disease can be so general, that it is often difficult to determine just what is causing the illness. Overall, we see chronic (long lasting or recurrent) inflammatory and infectious conditions involving the mouth, gums, sinuses, intestines, lungs, bladder, skin, eyes, and even the nervous system. Ill cats have a poor hair coat and progressive weight loss. Finally, they can suffer unusual forms of cancer and blood diseases such as profound anemia and abnormal decreases or increases in white blood cells.

Preventing infection can be challenging. Remember, the virus is most often spread through bite wounds from infected cats and the only way to prevent infection is to prevent exposure to the virus. However, many cats like to go outdoors and many cat “parents” do not want to deny their cat “child” that opportunity. Perhaps allowing your cat’s outdoors with your supervision is an option. Ideally, keeping them indoors with lots of cat-trees, toys and areas for window viewing is recommended. If you do have an FIV cat living with other cats, remember that spreading infection within the household is uncommon. Separating the infected cat from the rest of the household is the usual recommendation, if feasible. Most families tend to allow the co-mingling of their cats especially since FIV cats usually are living with other cats for years before their positive status is recognized. Even infected cats can live long healthy lives under the right conditions. In Idaho, we see very few cats who appear to be truly sick from feline AIDS. Most of the time, we find out a cat is FIV positive only after running a screening test on an apparently healthy cat!

Next Month, part 2 of this series will cover the controversial FIV vaccine and how it has complicated attempts to accurately diagnose infected cats.

I Didn’t Know Cats Can Get AIDS (part 2)

By: Alexis Higdon, DVM

Last month we discussed the history, known facts and prevention of Feline Immunodeficiency Virus (FIV). The main highlights stressed that FIV was discovered in California in 1986, it cannot be spread from cats to humans or other species, primary mode of transmission is through bite wounds, and prevention is best achieved by avoiding exposure to the virus. This month we will talk about the controversial FIV vaccine and how it has complicated attempts to accurately diagnose infected cats.

Prior to 2004 diagnosing a cat infected with FIV was quite easy. Veterinary hospitals and clinics have in-house blood tests that can determine infection in about 15 minutes. Tests were run on kittens, cat’s who had not previously been tested, all newly acquired cats, and any sick cat. Periodic testing of cats who go outdoors unsupervised was also recommended. The FIV tests look for markers (antibodies) made by the cat’s body in response to being infected with the virus. Kittens younger than six months of age may acquire antibodies from an infected mother cat, but usually do not themselves become infected. These kittens should be retested after their six-month birthday. Any cat who has been in a fight and bitten by another cat needs to be tested 8-12 weeks after possible exposure. This is because it takes that long for a cat’s body to produce antibodies after being infected by the FIV.

A “false-positive” test is one in which a positive result occurs, but the cat is really negative. Fortunately these are quite rare. However, since they do occasionally occur, a follow up test is recommended on any cat who tests positive for FIV. This test is called the FIV IFA (Immunofluorescent Antibody Test). In this test, a blood smear is submitted to a professional veterinary pathology laboratory. The pathologist then studies the blood smear under a special light source that illuminates the actual antibody attached to the surface of any cell infected with FIV. Visualizing these antibodies determines if the cat is persistently infected with FIV for life.

In March of 2004, the first FIV vaccine was introduced. A tremendous amount of research, effort and money went into developing the vaccine. The veterinary community and cat owners were thrilled with the prospect of having a vaccination against infection from FIV. However, the vaccine has sadly presented more problems than solutions. There are five FIV subtypes, A, B, C, D, and E. The vaccine is reported to be 82% effective against subtype A and D, only 2 of the 5 subtypes. One of the subtypes it works against (D) is not known to be present in the United States; the other subtype (A) is reportedly present only in the “western” United States. Subtype B prevails in the “eastern” United States, but is not represented in the vaccine.

There is even a greater concern with the vaccine. A cat inoculated with FIV vaccine will test positive to any of the tests used to detect FIV infection in a cat. Now, when a cat is tested for FIV, we cannot accurately determine if the cat is truly infected, or has been vaccinated, or is both infected and vaccinated. This problem creates confusion for both the veterinarian and the cat owner. Until a better vaccine is available, or different testing methods are developed, it is difficult to determine what is medically responsible regarding the administration of this vaccine. Veterinarians and cat owners need to be completely informed before making a decision regarding using the vaccine, and interpreting the results of FIV tests.

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