Feline Companions

Cat Care & Health

Feline Companions - Cat Care & Health

The Feline Leukemia Virus

Each year, we’re seeing more and more FeLV positive kittens born because there are too many cats on the street. One infected male cat feeding with a colony of strays can infect most if not all the cats in the colony. One infected female can do the same, and can produce positive kittens. (Note: A study has recently revealed that not all kittens born to a FeLV positive mother will carry the FeLV virus. Kittens may show a false positive elisa test result from antibodies received from the mothers colostrum.) Although the male does not pass the virus through mating, the female is likely to get the virus by grooming off the male’s saliva.

FeLV in Cats

Feline Leukemia is not cancer of the blood. That’s human leukemia. Feline Leukemia is a virus that weakens the cats immune system and leaves it open to infection, illness and disease. Two of the prominent illnesses FeLV positive cats fall prey to isLymphosarcoma (malignant cancer of the lymphatic system) and FIP, (Feline Infectious Peritonitis) a fatal virus. (Note: There is an intra-nasal vaccine against FIP.) Generally, FeLV positive cats live 3 to 4 years after becoming infected with the virus. We have had one positive cat live for 9+ years and we’ve had kittens expire at 3 to 4 months. Every cat is different, and with good nutrition and care, FeLV positive cats can live a very comfortable, although shorter than normal life.

The virus is carried in the body fluids; the blood, saliva and urine, and cats can contract it by eating and drinking from the same food and water as an infected cat or by using the same litter box or outside area, coming into contact with the urine of an infected cat. It is “Species Specific”, communicated between cats only, and is NOT contageous to humans. One lady who called said she foster cared a positive cat which sneezed on her cats and transmitedFeLV to her animals. Yes, it can be transmitted in this manner. The virus has a relatively short life span outside the cat. It can survive in a wet environment, such as a litter box, food and water, for several hours and on a dry surface for only a few minutes.

The virus is readily killed by a strong solution of hot, soapy water or a 5% solution of chlorine bleach and hot water. For litter boxes, wash first in soap and hot water, then bleach. Do not pour bleach solution directly into a soiled litter box as the combination of ammonia from the urine and chlorine is hazardous to both humans and animals when inhaled.

There are no obvious outward signs of FeLV. Positive cats look just like any other cat. Exposure to the virus is detected by a blood test. There are two blood tests used to diagnose FeLV. Most people do not understand the purpose of and difference between these tests. The ELISA, an Enzyme-Linked Immunoabsorbent Assay, is a simple blood test that can be done in the vet’s office. It is a test for the P-27 protein which has been found to adhere to FeLV virus antibodies. This test shows that the cat has been
exposed to the virus. It is not a test for infection with the virus and a positive elisa does not mean the cat has FeLV. Some cats are born with a natural immunity and not all exposed cats will contract the virus. All exposed cats will test elisa positive. For this reason, the vet will usually recommend that a positive elisa be repeated in a month. If the repeated elisa is negative, it means that the cat has successfully withstood exposure to the virus and is negative. The test results may not be accurate when performed on a sick cat as illness can reduce FeLV antibody production or on a kitten under 14 weeks of age due to the immunity provided by the colostrum. The second test is the IFA, the Immunoflourescece Antibody, also known as the
Immunoflourescece Assay and Hardy Test This is the definitive test for FeLV. Through use of a flourescent-labled antibody it shows a reaction that detects antigen present on or within cells. Special dyes and an ultraviolet microscope are required to see the reaction. It reveals the presence of live antibody production so as to establish the positive diagnosis. A cat can test positive on the elisa and later retest negative but a positive IFA will never repeat negative and is proof positive that the cat is infected. Several years ago, we took two elisa positive cats from another rescue group. They were brothers, both Flame Point Siamese. When I got them, I did the elisa test on both. One tested negative. I scooped him up and brought him to the vet, where they caged him, drew blood and sent an elisa out to the lab to confirm and document my test result. He was negative. Basing a positive diagnosis on an elisa alone would have condemned him to live out his life in a feline leukemia colony. So, why, you ask, don’t rescue groups do IFA’s on elisa positive cats? The cost. Some vets charge as much as $50 or more for an IFA.

Should FeLV positive cats be vaccinated? Absolutely, as long as the cat is healthy. No sick cat, positive or negative, should ever be vaccinated until it is well. Without vaccinations, they have no resistance to fatal viruses. Although they are not as effective as they would be in an FeLV negative cat, vaccines will allow their bodies to produce antibodies against the most common viruses, some of which are airborne. People have called and asked me if vaccinations cause skin cancer. I’ve heard it can happen but I’ve never seen it happen and it’s never happened to any of our cats.

So, what is one to do with a Feline Leukemia positive kitty?

For sure, it has to be kept away from negative cats. It should be in a comfortable, cozy environment, with frequent human contact, not in a cage. It should receive good nutrition. Illness or infection must be treated immediately and aggressively.

There is one very important point I want to make regarding the vaccine against Feline Leukemia. It will not protect the cat against continuous or frequent contact with an infected cat. If you have a positive cat, you can not adopt a vaccinated negative cat as a companion and expect that it will not conract the virus. The vaccine affords about 80% protection against accidental exposure.

There are about 9 different strains of FeLV. Not all are aggressive. One causes non-regenerative anemia, a condition in which the red blood cells are destroyed and the cat doesn’t have the ability to reproduce them. If you have a FeLV+ cat that becomes acutely anemic, it may have that strain of the virus. This can be determined by having a blood test called a “Reticulocyte Cell Count” done. Reticulocutes are newly formed red blood cells. A below normal reticulocyte count would indicate that the anemia is non-regenerative. Unfortunately, this condition is irreversable. Blood transfusions will not save the cat. Non-regenerative anemia is fatal.

Recently, I was asked a question regarding the transmission of the different strains of FeLV between positive cats in anFeLV colony. Two vets I conferreed with both agree that there is an extremely high likelihood that cats in an FeLV colony can pass different strains of the virus to each other.

We do not euthanize healthy positive cats. They have no idea that they have a fatal illness and they don’t worry about it. Without this worry, which plagues so many humans with terminal illnesses, cats can live without the stress that frequently makes the human condition worse. The cat just goes from day to day looking forward to doing all the things cats do.

Eileen J. Poole, A.C.S.

Questions or comments about Feline Leukemia or other cat related issues? We’ll be glad to help. Contact us By phone (New York City area) at (718) 847-3293 or e-mail at


Feline Companions, Inc.

P.O. Box 180303

Richmond Hill, NY 11418-0303

Tel; (718) 847-3293

e-mail us at: Felinecompanion@AOL.com

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