Feline Leukemia In Your Cat

I practice in South Florida where Feline Leukemia (FeLV) is the most common fatal infection that I see. Feline leukemia is caused by a retro virus that is spread cat to cat through prolonged contact, bites and from parent to offspring. The feline leukemia virus cannot survive long in the environment. It is killed rapidly by heat and drying. Once a cat is infected with FeLV it may live for a few months, a few years or a normal lifespan. Pregnant cats that carry the feline leukemia virus often pass the disease to their kittens while they are still in the womb. Mothers that do not may pass the virus on to their young kittens.

The majority of cats that are exposed to FeLV do not develop a fatal disease. Their bodies mount an immune attack against the virus, producing antibodies that cure themselves of the disease or keep it in check. In some of these cats the virus is completely eliminated from the body. In others it is held in check throughout their normal lives. Still others develop a fatal disease at a period in their life when stress or a compromised immune system allows the virus to proliferate.

Feline leukemia does not affect human beings and is not related to the leukemias that affect man. It does not affect dogs. It has been reported in lions, tigers and other large cats.

The signs of FeLV can include listlessness, weight loss, fever, pale gums (anemia), jaundice, enlarged lymph nodes and miscarriage. Because feline leukemia depresses the immune system a host of other maladies with varying signs often occur. Bells sound in my brain whenever a cat gets ill with minor problems too frequently. Many times feline leukemia has turned out to be the root of these problems.
Feline leukemia is a bit of a misnomer in that fewer than half the cats infected with this virus develop cancer. When they do it is not actually the FeLV virus that is at cause. It is that the body’s own cancer-fighting mechanisms no longer function adequately.
The diagnosis of FeLV has become very simple due to the development of in-office diagnostic tests that take only minutes to run on three drops of blood. The most widely used test is the SNAP test marketed by Idexx Laboratories . This test tests for FeLV and the Feline Immunodeficiency Virus (Feline Aids) simultaneously. It is a highly accurate test for detecting the presence of the FeLV virus. Cats that test negative have overcome the virus, not yet been exposed to the virus or are in the very early stages of the disease. Those that test positive have the virus but may still overcome or learn to live with it. Cats that test positive and show advanced symptoms of the disease will likely die from it. Occasionally a test result will be inconclusive. When this occurs regional laboratories can perform other more sensitive tests or the cat can be retested at the office in two-months time. Some feline specialists confirm all snaps-positive results with laboratory-run IFA tests. I leave this decision to confirm SNAP results at a lab, to the cat’s owners. Cats that test positive by any method should be isolated so that they do not spread the disease to other cats. Catteries should isolate new cats for three month, testing them at the beginning and end of the period. Vaccination for FeLV does not influence the test results.
As of the writing of this article there is no cure for feline leukemia. We can give these cats antibiotics to substitute for there weakened immune systems, appetite stimulants and vitamins to help maintain body weight and most importantly lower stress in their lives. Many FeLV cats are indoor/outdoor cats that are exposed to a number of outdoor health risks. The greatest of these is cat fights. Keeping these pets indoors can produce a temporary remission in the disease. Some veterinary centers administer anti-cancer drugs as well as human interferon. Neither of these medications will cure the cat and I am not convinced of their effectiveness in prolonging or improving these cat’s lives. Of the two, interferon produces the least side effects. There are reports that a recombinant feline omega interferon is more effective than human interferon. I have also not found high doses of vitamin C helpful. Prednisolone and other corticosteroids improve appetite and the cat’s sense of well-being. These steroids may also shrink certain lymphoid tumors present in the disease and combat anemia but they have no effect on the feline leukemia virus. Steroids can actually hasten the appearance of tumors in FeLV-positive cats.
There are excellent vaccines on the market to immunize against FeLV. I use one made of small portions (subunits) of the virus’ protein, which is manufactured by the Merial Pharmaceutical Group, PUREVAX LEUCAT . This vaccine gives excellent immunity when administered to kittens at nine and twelve weeks of age. In 2005, a jet injection system (Merial's VetJet Transdermal) has been introduced into the market that eliminates the need for needle injections. This might help prevent the rare occurrence of injection-site tumors in cats since the injection channel is very narrow. Immunity is said to persist for a year after a single injection to adult cats but this immunity may last longer. An occasional cat will have a mild allergic reaction or run a low fever after the vaccination but I have never experienced more serious side effects. No vaccine is one hundred percent effective. But most vaccinated cats are completely immune to FeLV. A few vaccinated cats will become temporarily infected when bitten by an infected cat or exposed to the virus, but then, because of their immunity, destroy the virus.
The feline leukemia virus is destroyed by most household cleaning agents. An excellent disinfectant is ordinary generic household bleach diluted one part bleach in twenty parts water. For the bleach to be effective, heavy soiling should be removed first with detergent. Several days in bright sunshine will destroy the virus in porous objects, as will microwaving damp microwaveable objects. However, Cornell University recommends infected premises remain vacant of cats for thirty days.
My clients frequently ask me when is it time to euthanize a feline leukemia cat. It is a difficult question that is never the same in any two cases. I tell them let it be as long as the cat appears happy. Many of my client’s cats remain healthy for a long time when they are kept in a sheltered environment and provided with good nutrition and health care. But there are other factors to be considered. Long term use of antibiotics in a household member (your cat) produces races of bacteria immune to these antibiotics. If these bacteria should later infect you, the infections may be difficult to control. Cats with FeLV often have unhealthy mouths. Should these cats bite you when you are attempting to hand feed them these bite wounds may become infected with bacteria. Keeping a FeLV-positive cat in a multi-cat household also exposes the other family pets to the disease.

The most important thing you can do for FLV-posative cats is to minimize stress in their lives. FLV-posative cats do best in single-cat households. The do better as strictly indoor cats rather than cats that are allowed to roam out of doors. The also do better when they are fed a high quality diet that is not based on fish. Cats with feline leukemia should receive a vitamin suplement. I suggest approximately one quarter milileter of a human pediatric vitamin suplement such as WalMart's Equate Brand or Visorbin Jr. The claws of these cats should be clipped blunt with a human finger nail clipper and then smoothed with an emery board. This is because scratch wounds in FLV-posative cats tend to become infected. FLV-posative cats are also more susceptible to ear and gum infections. Gum infections can be minimized by frequent brushing and periodic dental scaling which should be followed by two weeks of doxycycline antibiotic. Ear infections are best treated with an antibiotic/steroid ear medication such as Tresaderm or Panalog. These cat's body temperature should be monitored periodically. If the cat's temperature is above 102.5F the cat should receive a two-week course of broad spectrum antibiotics such as Clavamox (ammoicillin/clavulanic acid) or one of the fluroquinolones such as Batryl (enrofloxacinl). During the period the cat is on antibiotics it should receive a tablespoon full of plain yogurt each day.

Recently, several studies have found that the administration of feline omega interferon prolonged the life of cats that were positive for FeLV and or FIV. One of these studies, SURVIVAL OF SYMPTOMATIC FELV OR FELV AND FIV POSITIVE CATS TREATED WITH A RECOMBINANT FELINE OMEGA INTERFERON by Mähl P, Maynard L, Karine De Mari K, and Lebreux B used this product (rFeIFNw) in very well controlled clinical studies. This study concentrated on chronic mouth infections which are common in positive cats. 28 cats were given 500,000 units of this interferon per pound body weight, once a day for 5 days and 20 cats received a placebo. Cats receiving omega interferon lived, on average, twice as long as cats that did not receive the product. The period these cats were studied was only a half year so we do not yet know the effects of repeated administrations. To my knowlege, this product, sold by the Virbac Co. is not yet available in the US but is in Japan and Europe (See Threads below).

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4/12/06 Dear Dr. Hines,
I read with some interest your section on FELV and treatments. Approximately 6 years ago, my 1.5-year-old male cat developed a
suspicious scab that turned about to be a fibrosarcoma. As you well know, the overwhelming majority of cats under the age of 5 that present with a fibrosarcoma are FELV+. He was fine for several months, then over a period of 6-8 weeks had several bouts of vomiting/diarrhea/high fever that responded to antibiotics. Both my vet and I realized that his immune system was beginning to fail. So, with nothing to lose, we both researched potential treatments and decided on the Interferon Alpha 7 day on/7 day off protocol. The results have been nothing less than stunning. In the six years since we began the treatment, except for his annual check-up, he has only had 2 minor illnesses. For the first few years, we used to test him, thinking that maybe he was sequestering the virus. However, each and every time, he was viremic. I wish I could attribute it to a stable, low-stress environment or something else we
might be doing. We don't have to add vitamins or appetite supplements. All of his other blood work falls into the normal range. It is the Interferon and a high-quality diet. While I know my success might be anecdotal, the low cost and ease of administration of the drug make a viable treatment option. I also know that once a cat's condition has deteriorated too much, nothing can help. I hope that you will consider using the Interferon treatment and that it will find the same success as we have.
Thank you,
Rita

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10/25/06 Dear Doctor Hines,Please kindly note this modification to our previous mail (copy hereunder) : For any further clinical data on usage of feline interferon in veterinary medicine, please log on the following web site : http://www.vetinterferon.org instead of : http://www.vetcontact.com/interferon as indicated previously.With all our apologizes for the disagreement, Yours sincerely, Team Virbagenomega.com

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Virbagenomega
26/10/2006 10:58 Pour : ronthepetdoctor@yahoo.com
cc : (ccc : Emmanuel Hess/VIRBAC/FR)
Object : Supplier in the USA Dear Doctor Hines, We have noticed your interest for Virbagen Omega on your internet website, and we thank you for that, as well as your interrogation on the way of supplying with this product in the USA. Actually, Virbagen Omega is currently marketed in the main European Union countries and in Australia as well. Virbagen Omega is not available in the USA yet. From the USA, the feline interferon can be obtained by the veterinary practitioners with a Compassionate Use Dispensation (a form to be filled out from the FDA) and ordered from a wholesaler in a country where it is available. For further information on practical and delivery aspects please visit the following web sites :
http://www.dr-addie.com/stomatitis.html#ifn and http://www.dr-addie.com/stomatitis.html#ifn https://www.abbeyvet-export.co.uk Should you need any further clinical data on usage of feline interferon in veterinary medicine, the following web site may be helpful : http://www.vetinterferon.org Thank you for your interest in Virbagen Omega.
Yours sincerely, Team Virbagenomega.com

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10/25/06 I try to post any interesting emails I receive. But please remember that many statements and claims on the internet and elsewhere are untrue or mistaken. If you can confirm or refute any of this information please let me know. RSH

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