(dedicated to Oliver and countless other cats whose lives have been mercilessly shortened by this virus. We will all meet them again at the Rainbow Bridge.)

PLEASE NOTE: This FAQ is dated 1995. There are no plans to update this reference. I believe the materials to still be useful to cat owners, but I recommend you do an Internet search, such as at www.google.com on Feline Leukemia Virus to gather more current information. A good place to start is http://web.vet.cornell.edu/public/fhc/felv.html



Last updated April 20, 1998.


    • Written by Erin Miller [


    ] with help from James Golczewski, PhD; Edwin Barkdoll, DVM-to-be; Cindy Tittle Moore; Jeff Parke, DVM; C.M. Newell, DVM; Barb French; Richard Kinoshita; and Ann Huber. Additional thanks to Wilf Leblanc, Dan Kozisek, Karen Kolling, Isako Honshino, Patty Winter, Harold Lemon, Jill Kronstadt, and many members of the Cat Fanciers’ Internet Mailing List for their comments.

The purpose of this FAQ is to answer frequently asked questions about the Feline Leukemia Virus (FeLV). The Feline Leukemia Virus is a virus which suppresses your cat’s immune system. A cat that becomes infected with the virus becomes susceptible to many ailments or breakdowns in its system. The virus was somewhat inappropriately named because it is different than the disease Feline Leukemia. A cat that tests positive for the virus will not necessarily contract the disease Feline Leukemia. However, cats that do test positive for the virus are more likely to catch any one of a number of diseases including, but not limited to, leukemia, lymphoma or opportunistic infections. This FAQ is divided into two parts; the first consists of information every cat owner should know or should ask about the virus. The second part is information for people whose cats have tested positive for the virus.

PART I: General Information about FeLV

What is Feline Leukemia Virus and can I catch it?

    Feline Leukemia Virus is a virus that is specific to cats only. It is considered to be the most common cause of serious illness and death in domestic cats. It causes a breakdown in your cat’s immune system causing your cat to become susceptible to many diseases which it might otherwise be able to fight off. It CANNOT be transmitted to humans (including children) nor can it be transmitted to other species such as dogs. The National Cancer Institute and the National Institutes of Health have written a CancerNet Factsheet which is available via gopher. See the References section for more information on this.

I’ve heard FELV is like AIDS. Can I catch AIDS or anything else from it?

    • People often use the “it’s like AIDS” phrase to describe a number of illnesses in the animal (and human) community with the idea that most people know so much about AIDS that this analogy is useful. Unfortunately most people don’t know much about AIDS and the resulting effect is to scare people out of their wits and have them dump their cats or dogs at the nearest pound because they are so deathly afraid of AIDS. They are similar to AIDS in that they affect and weaken the body’s immune system. The ONLY similarity between FeLV, FIV (Feline Immunodeficiency Virus) and FIP (Feline Infectious Peritonitis) is in their genetic makeup. All are RNA (as opposed to DNA) viruses, and FeLV and FIV are what are known as “retroviruses.” FIP is a “coronavirus.” (See the


     for more information on this disease).

What is a retrovirus?

    Retroviruses carry with them an enzyme that causes a process to occur in the DNA known as “reverse transcription.” RNA normally pairs up with DNA, copies itself, and thus increases/replicates itself. When an RNA retrovirus does this, it fools the DNA to copy *it*, instead of the normal RNA, thus causing even more of the retrovirus to be created. So as long as a particular cell is affected with the retrovirus, that cell will be affected for its whole life. One would have to kill the cell before it reproduces to eliminate any chance of that cell making any more FeLV or FIV RNA. This is one of the reasons why it is so difficult to get rid of, because you must kill all the cells which contain the virus, and attempting to do this may either kill the animal itself, or it is simply impossible to tell which cells have the virus in the first place. Basically, a retrovirus is a parasite at the genetic level, a DNA-tapeworm, if you will.

How is it transmitted?

    FeLV is transmitted via saliva, mucus, urine, feces and blood. This means mutual grooming and biting/fighting are the most likely methods of transmission, although sneezing, hissing, sharing food/water bowls and sharing litter boxes are also possible means of transmission.

Will I infect my healthy cat if I pet an FeLV+ cat, then pet my cat?

    No. Not unless you were to go immediately from one cat to another, and have wet saliva, urine or blood on your hand. Even then the chances would be slim. FeLV needs to be transferred through the media above, and will not live long outside the host (the infected cat). Warm, dry environments will deactivate the virus and common household detergents and disinfectants will eliminate it from any contacted surfaces. If you wash your hands with soap after touching an infected cat, you will not infect an FeLV negative cat.

What does the virus do to a cat?

    In sum, once the virus gains entry (usually via saliva or mucus membranes) it will reproduce in the lymph tissue which is your cat’s first system of immune defense. Some cats are able to mount a successful immune response against it and defeat the virus at this stage. In cats who don’t successfully destroy the virus here, the virus will then move into the bone marrow where red and white blood cells are produced. It may stay latent in the marrow for many years. After that it will attack other tissues, including possibly causing a breakdown in several stages of the immune response system.

Is there a vaccine?

    • Yes, there are several commercial vaccines available. Unfortunately the USDA does not have standard requirements for FeLV vaccines, so different manufacturers can publish ‘Effectiveness Ratings’ which cannot be compared with each other due to a lack of uniformity in testing terms and requirements. Estimating the effectiveness of the vaccines is difficult and most vets I’ve spoken with estimate them to have ~75-85% effectiveness (this means cats challenged with the virus will fight off infection 7-8 times out of ten). Published studies show that there are irreconcilable differences and bias in Effectiveness Ratings put out by the manufacturers so currently it is impossible to estimate the actual effectiveness of and between vaccines. Suffice it to say that your cat is MUCH better off trying to fight the virus having received the vaccine, but the vaccine is not 100% effective so you should not expose your cat to undue risks. (Note: NO vaccine, whether it be for cats, dogs or people, is 100% effective. Some are about close to being as fully effective as possible, however the FeLV vaccine is not one of them).


    Since writing the first version of this FAQ, I’ve had a number of people tell me that a cat has only a 30% likelihood of catching the disease, and even then if only in persistent close contact. I have found nothing in the recent literature to support this claim, and every veterinarian I have spoken with states that the likelihood of becoming infected depends on the level of exposure, which vary in different locales and situations. Since most tests are done in controlled situations, it would be impossible to come up with true “real world” statistics. In one vet’s words “But what if it is only 30%? Would you stop wearing seat belts if there was only a 30% chance of serious accidents if you commuted in a car every day? I hope the odds are far less than that … and yet I still hope you are taking the appropriate safety cautions. Unless the vaccine has been proven to cause serious harm, it is a good precaution to take, regardless of the percent chance of disease transmission.”

If I don’t get my cat vaccinated, what are its natural defenses against the virus?

    According to the literature, neonatal kittens are 100% susceptible to catching the virus from one exposure. 8-week-old weanlings are 85% susceptible from one exposure. There is serious debate over the likelihood of non-vaccinated, healthy adult cats becoming infected with the virus but it seems that ~40% of cats exposed become immune, ~30 percent become persistently infected (show acute signs of a related-disease) and ~30 percent become infected, but the virus is latent in their system. (Hardy, et al, 1980).

Is the vaccine expensive and how often do my cats need to be vaccinated?

    After your cat has gone through its more elaborate set of kitten-shots, the FeLV vaccine should be given once a year. If you adopt an adult cat and don’t know if it has been vaccinated for FeLV, start it immediately on its annual shots. If you are unsure if your adult cat needs be vaccinated, talk to your vet. Prices vary between vets, locally and nationally. I surveyed readers of rec.pets.cats and contacted vets around the country and found that prices for the vaccination alone cost between $9 and $30 dollars. The average was $18 (not including the vet-visit charge). It seems that the FeLV test costs about the same, but I didn’t do a full-scale survey.

If I get my cat vaccinated, isn’t there a chance that it will catch the virus from the vaccine?

    No. As of July 1992, all of the vaccines which are approved for sale in the United States are incapable of causing a positive FeLV test result. (Sorry, but I don’t have figures for vaccines in other countries. If anyone does, feel free to append them onto this FAQ.)

Is there any risk in getting my cats vaccinated?

    • There is always a risk that your cat may have a bad reaction to a vaccine, ANY vaccine. It is a good idea to wait in your vet’s waiting room for 30 minutes after receiving a vaccination, ANY vaccination, to make sure your cat does not have an adverse reaction, and if it does the vets will be on hand to deal with the situation.


    There is also some evidence that vaccinations in general may be the cause of tumors (known as postvaccinal sarcomas or fibrosarcomas). The chance of this happening is estimated to be approximately 1-2 in 10,000, but you should be aware of it nonetheless. This has not been limited to FeLV vaccines, in fact it was originally thought to pertain solely to rabies vaccines, but this is not thought to be the case any more. Since this form of cancer seems to have a high recurrence rate, and little is known about it, if you have *strictly* indoor-only cats, you may want to discuss with your vet if the risk of fibrosarcoma is greater than the risk of being exposed to FeLV if the cat gets out. This is an individual decision that will be different for each household. You should contact your vet immediately if you notice any lumps in the vaccine injection area.

Do I have to get my cats vaccinated?

    No one can force you to vaccinate your pets, though there are laws in some areas regarding certain diseases like rabies. Check with your vet to see what vaccines are required in your area.

My cats are indoors-only. Why should I bother getting them vaccinated?

    • The answer to this question all boils down to a risk/benefit assessment.


    • If you live in a high-rise, do not plan on moving in the next year, and do not plan on exposing your cat to other cats (such as getting a new kitten, or temporarily housing a stray), then there is really no need to get the cat vaccinated. If it is somehow possible for your cat to make it to the outside world, whether it be because of a break-in, or a landlord who forgets to close the window they just fixed, or a visitor doesn’t realize the cat is not allowed outside (all of which are real-life cases of people I know whose indoor-only cats have gotten outside) then your cat is at SOME risk. Many people who lived through Hurricane Andrew or the LA Earthquake can tell you that some of their indoors-only cats ended up on the street for days. Fortunately disasters like these are infrequent, but the point is accidents can happen. In the few hours or days that your cat is outside it could come in contact with an infected cat, and it is better to give your cat that 75-85% boost to its natural resistance.


    But, some people feel the risk of adverse reaction and possible fibrosarcomas from vaccinating are not worth the risk if the cat is not likely to go be exposed to FeLV+ cats, even if it did get outside for a short period. What YOU as the cat’s owner (not your vet, not your cat’s breeder, not your friend of a friend who knows a lot about cats, and not someone who wrote something you read on the internet) must decide is how much risk is there for your cat getting out and being exposed, and is that risk worth the other risks associated with the vaccine?

My cat is a purebred, and I’ve heard the vaccine should not be given to purebreds. The breeder I bought the cat from discourages getting the vaccine.

    • This is a touchy subject because there is often the general feeling among vets that many breeders don’t know what they are doing, and the feeling among breeders that vets don’t know much about purebreds. There is probably a little bit of truth to both sides. It is true that some breeders may think they understand veterinary medicine better than they really do, and unfortunately rely on word-of-mouth advice of other breeders rather than vets (eg: “Jane Smith has been breeding for 15 years and she knows a lot so if


    •  doesn’t like this vaccine, it must be bad”). But it is also true that most vets do not deal specifically with purebred issues. There is no course in vet school called “Purebreds 101” and vets are often just as guilty as anyone in misidentifying mixed breeds as purebreds, of being too quick to diagnose a “breed specific” illness with less data than if they would if the cat were not a purebred, or of not being aware of conditions which may affect one breed more than another.


    • Keep in mind that some veterinarians are also breeders, or work within the CFA, TICA, ACFA (AKC for dogs) or other purebred registries, and these vets are most likely going to be more knowledgeable about conditions which are more common to certain breeds. Also remember that not all purebreds are the same, each breed is different and has its own characteristics. Just like you can’t say “don’t vaccinate Europeans for smallpox,” because there are *many* different cultural and ethnic groups in Europe.


    • The immune system of purebred cats has


    • been tested to determine if it is different than that of mixed breed cats. It is impossible to state one way or another if the purebred immune system, because of inbreeding, has any reason to adversely react to vaccines that are tested on a largely mixed-breed cat population. Some people feel there is a significant difference between the two based on antecdotal evidence and won’t vaccinate for that reason, and some people feel this is nonsense.


    • But that doesn’t answer the question because this one is going to have to be answered by you and your own gut feeling. Who do


    •  trust more with the combined necessary knowledge of vaccines, as well as about your purebred? Talk to your breeder and see if s/he is aware of the vet literature, or is repeating word-of-mouth arguments. Many of them are well aware, many read the literature more than vets do, so don’t be afraid to ask them why they hold the opinions they do. Talk to your vet and ask how familiar they are with your partiuclar breed of cat as well as purebreds in general. Get a feel for both. Keep in mind that many breeders do not vaccinate their own breeding cats because FeLV vaccines can cause miscarriages and stillbirths, or it may just be cheaper for the breeder to test their cattery every year and every cat that comes into the cattery rather than to vaccinate, especially as cats from a cattery are less likely to escape to the outside world (remember the risk/benefit assessment above). Make sure you find out

exactly why

     the breeder does not recommend the vaccine as it may very well be that the breeder has had numerous negative experiences with the vaccine in his/her particular line of cats, and that your cat may be genetically predisposed to have a bad reaction. If this is the case, you should still discuss the matter with your vet, and it may be best not to get the vaccine.

My cat gets sick after it gets vaccinations. Why should I put my cat through that?

    Some cats do have bad reactions to vaccines. However, it is better to have a cat sick for one day per year from being vaccinated than to have it die a miserable death from an FeLV-related disease. If your cat has a bad reaction to a shot, ANY shot, and the reaction lasts more than 12-24 hours, you should immediately bring your cat to the vet. Even if your cat has a mild reaction, you should at least discuss the matter to see what are the best options for next year’s vaccinations. It may be best to spread your cat’s annual vaccinations out over a few months, or have them all administered at once. If your cat has had a *very* bad reaction, it very well may be best to discontinue vaccinating for FeLV. Definitely discuss this with your vet.

I already have a cat(s) and I found another which I want to bring home. What precautions should I take regarding FeLV (and other diseases)?

    • This depends on the environment the new cat comes from. If it is a stray, or from a shelter which does not routinely test for the viruses (make sure you ask this of any shelter you visit), or from a household where you have reason to doubt the person has had the cat tested/vaccinated, then keep the new cat separated from yours until you can have a vet examine it for many things. Keep it in a separate room and provide its own food dish, water bowl and litter. DO NOT let your cats share any of these things, or share the same space, until your vet checks out the new one. If it is a stray cat, it may never have been vaccinated against FeLV and Rabies, or if it was a housecat it may be past its time for an update and have been exposed. Cats which have been on the street may also have fleas, tapeworm, ringworm or other parasites which are transmittable to you and your pets.


    One of the most unfortunate situations that occurs far too often is when someone, out of the kindness of their heart, takes in a stray or unwanted cat — either permanently or in the hopes of finding it another home. This is often done spur-of-the-moment, and unfortunately sometimes has dire consequences. If you find a cat in a bad situation and you want to help it, keep it isolated or ask your vet to board it until all the test results have returned. It is never worth the lives of your current pets in an attempt to save another.

How is FeLV detected?

    • Your vet will do a blood test; there are two types of blood tests which can be performed. Some vets will automatically do one of the tests before vaccinating your cat to make sure it is not already positive for the virus. The first (ELISA test) is where the vet takes some of your cat’s blood, mixes it with a chemical and watches for a color change. If the blood changes color then your cat has tested positive for the virus. False positives are not uncommon in this form of test, so if your cat tests positive it may be a good idea to have it retested. “Light positives” are where the treated blood only changes color slightly. This means your cat is infected with the virus, but the virus is not very active in its system. The second type (IFA test) involves sending the blood sample to a special lab. This lab tests to see if the virus is being produced in the bone marrow. If this second test is positive, it is unlikely that your cat will ever test negative. Below is a flow chart (from a lecture by Dr. William Hardy, U of Penn. Vet School) which depicts what you should do if your cat tests positive on the ELISA test:


    • If positive:
      • whether healthy or sick, confirm by Indirect Fluorescent Antibody test (IFA)


    • If negative:
      • if healthy and not exposed to a positive cat then no need to retest
      • if healthy but exposed to a positive cat then retest in 3 months because the healthy cat may be incubating the virus.
      • if sick then confirm the ELISA test with an IFA test

So some cats who test positive can later test negative?

    Yes. If you have a cat which tests positive on the ELISA test, you should immediately have an IFA test done. If it tests negative on the IFA test, you should have your cat retested with the ELISA test in 3 months. If a cat does not test negative again in roughly three months, chances are it will always test positive. Vets and virologists have devised an entire classification scheme of the different types of infected cats (transiently infected, persistently infected, etc.) based on the ELISA and IFA tests. It can be very confusing and if you are interested in learning the details you should consult with your vet regarding your particular cat’s status.

Is it possible for a cat to test negative when it really is positive?

    Unfortunately, yes. Although false negatives are not very common, they do occur, especially if you are dealing with a young kitten. Sometimes the cat has been recently exposed to FeLV, so the antibodies have not yet had enough time to build up enough of a response to appear on the test. To be absolutely sure a cat is not FeLV+ you should test it twice, a few weeks apart (the cat should remain isolated from other cats during this period, too, otherwise there is little point in doing a second test). The likelihood of getting a false negative is increased depending on the nature of the test. The ELISA test will show more false negatives than the IFA test. Some mail-order catalogues now offer FeLV testing kits using saliva or tears as the medium. These are more likely to trigger a false response than the ELISA test which uses blood. Fortunately, the false negative rate on the ELISA test (which is what most vet offices use for standard FeLV tests) is low enough that most people don’t bother with the second test.

How long does a cat who tests positive have to live?

    There is no set time period for how long an FeLV+ cat will live. One person on the internet said they had a cat which lived for 20 years with the virus, while others have given dates as long as 10 or 12 years, although these are probably extremes. I have not found any truly long-term studies to document, but it seems that of the studies done, 83% of FeLV+ cats do not live beyond 4 years. (Hardy, et al 1980). All cats which do not later test negative, but in all other ways are healthy, are carriers for the virus. Even though they do not have acute symptoms, they can still spread the virus to cats which are not infected. Often people do not have their cat tested for the presence of FeLV until the cat is noticeably sick, and by this time the FeLV-related disease may have progressed too far for the cat to recover.

What are symptoms for which I should be on the lookout?

    Unfortunately, since FeLV is a retrovirus that attacks your cat’s immune system, your cat can become ill from many things as a result. This makes looking for a ‘sure sign’ very difficult. Often the immune system is weak so your cat will become chronically infected with certain conditions such as stomatitis, gingivitis, oral ulcers, abscesses and non-healing wounds of the skin, upper respiratory infections or FIP. Some cats whose digestive tracts are affected have been described as staring at their food bowl seemingly unable to remember how to eat, or their breathing will be very difficult and loud. Basically, whenever your cat shows chronic, peculiar and/or unhealthy behavior, take it to a vet to be examined.

My cat recently passed away from FeLV. How long should I wait before getting another cat and are there any special precautions I should take?

    • Well, your own grief issues aside, from a medical point of view you do not need to wait very long. The virus is fragile outside the host, and I know of one vet who has even stated that it would be safe the next day. Personally, I would wait a week at least. You should definitely discard the litter box and food/water bowls, or else clean both well with household detergents or a 1:32 bleach solution.


PART II: If your cat has tested positive

Some of these points are mentioned in the general section above, but here are more specific questions geared to people whose cats have tested positive. The most important point to stress is that FeLV+ cats *MUST* be made indoors-only. This needs to be done for two reasons. First, the more you expose your cat to outside ills, the more likely it is to contract an FeLV-related disease or infection. The second reason is that FeLV+ cats are like Typhoid-Marys to any other cat they meet. As noted above, the vaccine is only 75-85% effective, so any vaccinated cat that your cat encounters is at risk, as well as any unvaccinated cat. If these cats are then infected and they continue to interact and infect other cats, then you could give rise to an epidemic in your area. If you cannot or will not keep your FeLV+ cat indoors, than the only humane thing to do is find a home for it with someone who will (ways to do this are suggested below), or have your cat put to sleep. This may sound extreme, but it is extremely selfish to allow your cat to roam the neighborhood possibly infecting all the local outdoor cats just because you refuse to keep your cat indoors. Keeping your cat indoors is one of the responsibilities of owning an FeLV+ cat.

My cat has tested positive. Should it be put to sleep?

    • The mere fact of testing positive is not enough to merit putting a cat to sleep, although there may be other significant factors involved which do make putting the cat to sleep the best option. There


    •  vets who recommend putting all FeLV+ cats to sleep. If your vet recommends this and you feel comfortable with that decision, then that is the best solution. Sometimes putting an FeLV+ cat to sleep


    •  the best option for the cat, especially if it has acute symptoms and is in pain. This is never an easy decision and one which should not be taken lightly. If you do not feel you are capable of emotionally dealing with having an FeLV+ cat (or cannot keep the cat indoors), but do not want to put the cat to sleep, there are other alternatives which are discussed below. The one thing you should not do is ignore the virus. If your cat has tested positive, then you have a responsibility to take some action.


What will happen to my cat now that it has tested positive?

    Because there are so many different ways to respond to the presence of the virus, it is impossible to predict exactly what will happen (and when it will happen) to your cat. I’ve noticed that any 5 vets you ask will give you 5 different answers to this question. The scientists who experiment and publish on the disease are also in disagreement. I have presented two different (published) viewpoints below. According to Hardy, et al (1980), (and these people seem to be the authorities on the disease) roughly half of all cats who test positive (and do not test negative again within a three month period) are persistently infected and show acute signs of FeLV-related diseases. The other half are latently infected and are in all other aspects ‘healthy’ although they are still carriers. 17% of all cats which test positive (and do not later test negative) will live past 4 years. The next point of view is taken from a much more recent article and has radically different statistics. According to Loar (1993), of cats which test positive for the disease only 5% will immediately become infected with an FeLV-related disease. The other 95% will enter the latent phase which will last for months to years. These 95% are still carriers for the disease and can infect other cats.

Although my cat has tested positive, it is healthy in all other respects. How can I prevent an FeLV-related disease from becoming active in its system?

    There is no sure way to keep your cat healthy. Eventually, an FeLV-related disease will probably develop no matter what you do. However, one way in which a disease is likely to develop is if you stress your cat’s system. If a cat’s system is stressed, its body can’t put as much energy into fighting off illnesses (just like you always seem to get sick during exams or when you have to make a presentation to your boss). “When all my cat does is eat and sleep 20 hours a day, how can it possibly be stressed?” you may ask. Anything which is upsetting or unpleasant for your cat may stress it, such as going for very long periods without food or water, overcrowding, movement to new territory, territorial conflicts, sending your cat to be boarded for long periods of time, or pregnancy and lactation. (Of course one should NEVER breed a FeLV+ queen as it will expose not only the tom, but all the kittens will be FeLV+. There is also an indication, although no proof, that FeLV causes abortions in queens. For the same reasons, neither should FeLV+ toms be bred.) Basically, keep in mind things which you have noticed in the past that seriously upset your cat. These are things which are more likely to lower your cat’s natural immune system and give a disease the chance to attack.

I have an FeLV+ kitten that I have decided to keep. Should I have it neutered/spayed?

    I’ve only encountered one case of a vet recommending not to spay a kitten because it was FeLV+. Unfortunately, going into repeated heat cycles was very stressful on her, and that owner believes it caused her to suffer ill effects of the disease sooner than she may have otherwise (of course there is no proof to this). It is true that there is a small added risk to anesthetizing an FeLV+ cat, but that risk will well worth the alternatives. Especially since a whole cat will have a very strong desire to roam, thus further spreading the disease. In my personal experience, my vet did a very careful screening to make sure my FeLV+ cat could handle the anesthesia before operating. It really should not be much of a problem, but always make sure if your cat needs surgery that you remind the vet and staff that your cat is FeLV+.

Should I continue to vaccinate my cat if it is FeLV+?

    The literature recommends against continued FeLV vaccinations. Other feline vaccinations (panleukopenia, rabies, etc.) should be continued.

I have had several cats for a long time. One of them recently tested positive, but the others have not. Do I need to get rid of the FeLV+ one?

    This is a tough situation, for which there is no pat answer. You should discuss the matter with your vet. One vet I spoke with felt that chances are the other cats have already been exposed and it is probably best to just keep them up on their vaccinations and not change the household drastically. One study (Barlough, 1984) says that in a survey of 45 households from which FeLV+ cats were removed, 99.5% of the FeLV- cats remained negative. However households in which the FeLV+ cats were not removed had infection rates 40 times greater. It is probably best to remove the infected cat if it can be sent to a good home without causing too much disruption in your household, and your mental psyche.

I have an FeLV+ cat and I want to find it a playmate. What should I do?

    • There a few options. The only thing which you really ought NOT to do is get a healthy cat as a playmate or let your cat outside for excitement. Dogs cannot become infected with the Feline Leukemia Virus, and some dogs and cats, especially those raised together can be very close. One word of warning: getting a dog (or any pet) for the sole reason of keeping a cat company is not a good idea. If you consider getting a dog, make sure you understand the amount of time and responsibility that goes into caring for a dog (which is much more than that of a cat); otherwise you will regret the decision and both you and the dog will suffer. (There are excellent

dog FAQs

    •  which will give you as much information on the matter as you can handle).


    Another option is getting a second FeLV+ cat. The obvious down side is that you not only have twice the vet bills, but you also put yourself at risk for twice the heart-ache when one or both become ill. However, if you are willing to take the risk you can search for FeLV+ cats by putting an ad in the newspaper and calling all your local vets and animal shelters and explaining your situation. They may put you on a list and should they receive any cats which test positive, they may give you a call. Make sure you give your current vet as a reference as most shelters and other vets will want to make sure you understand the responsibility of owning an FeLV+ cat or to make sure that you are not some psychopath looking for sick kitty-cats to do nasty things to (of course most people, especially your relatives, will think you are a psychopath anyway, for keeping and seeking out more FeLV+ cats).

I have an FeLV+ cat that is otherwise healthy, I do not want to put it to sleep, but I can’t keep it. What can I do?

    • Similar to the above answer, place ads in the newspaper and contact your local shelters and vets and tell them you have an FeLV+ cat which you are willing to give to a good home. A good home is someone with another FeLV+ cat, or someone who does not have any other cats and will keep the cat indoors. Also, there are animal shelters which specifically take in FeLV+ cats. Again, contact your local vets and shelters to see if they are aware of any such haven to which you could send your cat. Almost all regular shelters will put to sleep any cat they receive which tests positive because the virus is so contagious. If you are going to do this, however, you should understand that is it unlikely that you will get instant results. If you expect to find a new home for an FeLV+ cat within a few days of making inquiries, you can pretty much forget it. Be prepared to hold on to the cat for a few weeks at least, while searching for a new home.


    • If you choose to put an ad in the paper you MUST take the responsibility of making sure the people who express interest in your cat are doing so for legitimate reasons. You should interview them in person and check references if possible. There


     people who will lie to get cats to feed to other pets, to sell to labs or to abuse. Think about this as you interview each potential candidate.




  • CancerNet Factsheet is available via gopher to gopher.nih.gov following the menu path Health and Clinical Information/CancerNet Information/Fact Sheets from the NCI/Risk Factors and Possible Causes. Or you can call the Cancer Information Service toll free at 1-800-422-6237 (1-800-4-CANCER).
  • Hardy, William D., Essex, Myron, and McClelland, Alexander J. (eds). Feline Leukemia Virus. Elsevier/North-Holland, Inc. New York, 1980.
  • Loar, Andrew S. “Feline Leukemia Virus: immunization and prevention” in Veterinary Clinics of North America: Small Animal Practice. 23(1):193-211, 1993.
  • Barlough, J.E. “Seriodiagnostic aids and management practice for retrovirus and coronavirus infections” in Veterinary Clinics of North America: Small Animal Practice 14(5):955-969, 1984.
  • Olsen, R.G. et al “Oncogenic viruses of domestic animals: in Veterinary Clinics of North America: Small Animal Practice 16(6):1129-1144, 1986.


Additional Readings

  • Hardy, W.D. Jr, et al. “Biology for Feline Leukemia Virus in the natural environment” in Cancer Res. 36:582, 1976.
  • McClleland, A.J. et al. “Prognosis of healthy Feline Leukemia Virus infected cats” in Rev. Cancer Res. 4:121, 1980.
  • Rojko, J.L., and Hardy, W.D. Jr. “Feline Leukemia Virus and other retroviruses” in The Cat: Diseases and Clinical Management, NY: Churchill Livingston, 1989.
  • Rojko J.L. et al. “Reactiviation of latent Feline Leukemia Virus infection” in Nature (Lond.) 198:385, 1982.
  • Also, the Journal of the Am. Vet. Med. Association, 199(10), Nov. 15, 1991 is devoted entirely to feline viral diseases.

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