Infectious Disease - Feline Leukemia


Infectious Disease - Feline Leukemia

Question: Two years ago I found a young female cat on the farm where I was living. It took 3 months of daily feeding her before she would let me close enough to pat her. By that time, of course, she was pregnant. I brought her into my house where, six weeks later, she had 3 kittens (2 males, 1 female). Mom and her children have never been outside since mom moved it. When the kittens were 7 months old, I had them all "fixed" and get all their shots. However, this year at their 1st annual checkup, we discovered the males did not get the Fel-Luk test or vaccination. So the vet did the test and both tested negative. Ivory got his vaccination, but Freckles had a slight fever and had not been feeling well for a few weeks (loss of appetite, weight and coloring), so the Dr gave him some antibiotics and said he'd get all his shots in two weeks. Later that afternoon, the Dr called to tell me that a recheck of Freckles' test showed a very slight positive, so he would need to be rechecked on his follow up visit in two weeks. This week Freckles had his follow up visit, and they did just the Fel-Luk test (not the combo test previously done) and again he showed a very slight positive. The Dr also said he feels something in his stomach/intestinal area and has put him on 1cc of Interferon daily. I've been reading all I can find on Fel-Luke and Freckles does show symptoms, although after the antibiotics kicked in, he began eating again and has regained 1/4 lb during the two weeks. My question is this. Can an indoor cat get Fel-Luk when its mother and siblings have all tested negative? Thank you for your time and assistance. Hazel

Answer: Hazel- It would be pretty unusual for a cat that was only exposed to its mother, who has tested feline leukemia negative, and then kept inside away from exposure to other cat to come up positive for feline leukemia. However, it is not impossible for this to happen. Feline leukemia is difficult to totally rule out because the virus can live sequestered in the bone marrow or central nervous system but not be present in the blood stream in some patients. When this happens, blood tests are negative but the cat still has the virus. If there is a stressful event in its life the virus may re-emerge. If the kitten's mother was an inapparent carrier of the virus but did have a period of viremia during the pregnancy it is conceivable that the kittens could have been infected while she was pregnant or when she was nursing them. This is not a highly likely scenario, it is just a remote possibility. I think that it would be best to try to confirm the results of this test by using a different testing technology. The best way to do this would be to send out an IFA (immunofluorescent assay) test to a reference lab. If this test was positive then it would be very likely to be a true positive. The in-office tests for feline leukemia virus are very accurate but still have a very big chance of being wrong in a situation in which they are being used as a screening test for cats that appear healthy. In this scenario, due to the overwhelming chance that the cat will actually be healthy, false positive tests are actually more common than true positive tests. This was discussed in this issue of the VetInfo Digest. I am hoping that Freckles will be in the majority of cats who have a false positive test in this scenario. Mike Richards, DVM 8/2/2001

Feline leukemia test results and exposer to positive kitten

Question: Dear Dr. Mike, I have a question regarding my felv positive kitten. This is long but I feel I need to explain alot of things. First I'll try to give you some history. I'm a vet tech and I've been working at a vet's office for about 5 years. We sometimes take in stray kittens and cats and find them homes. We would always test the adult cats for felv but we never tested the kittens. The vet didn't think it was likely the kittens would have felv and plus the added expense of testing them and so he didn't think it was necessary to test kittens for felv. Well this year we've all learned our lessen. A kitten we adopted out last year came back this year very very sick and we tested it for felv and it was positive and it was euthanized. It was an inside cat. Two of the kittens we had this year went to a Vet Tech school and were going to find homes through there. I had tested them both for felv before they left because I knew they'd be put to sleep immediately if they had it and I didn't want that to happen. Both kittens tested negative with the Idexx Snap test when I tested them. Three days after I tested them and they were at the vet school they were retested with the wells test and one tested a very faint positive. That one did have a URI. They tested him the next day again with the wells test and it was a weak positive and they put him to sleep. They wouldn't give the kitten back to me like I wanted so I could do an IFA test. I was very mad at them cause I tested him as negative and I know the wells test isn't very accurate. The other kitten they had they retested 2 weeks later and he tested positive on the wells, they tested him again on the wells and it was neg and then they tested him with the Snap test and it was neg so they found him a home. Because of all that we felv tested all the kittens we had left at the vet. One tested a very faint positive on the Snap test. It was a kitten I had bottle raised since it was 2 or 3 days old. We did have a kitten I caught in the woods outback of the vet that was very skinny but I got it back to good health and I didn't get a chance to test him before he got adopted and I"m thinking maybe this one had it but I don't know for sure. I'm saying that because I just don't know from who this virus came from. We do vaccinate the kittens for felv at the 3rd round and most of the kittens we had at the time we tested them had had 2 felv vaccs. Maybe the baby kitten I raised had had it all it's life but my opinion was that if he had it since he was born it would have been a strong positive but I don't really know. This kitten is now 6 months old and is doing perfectly fine. I've retested him with the Snap test 3 times and he's been a very faint positive each time. I recently sent out an IFA Felv and he was positive. I always have my bottle raised kittens with me until they find homes and so I had the one that eventually tested positive (Tiger) and one other one which was a calico. I got them on the same day and they were both about 2 or 3 days old and they were raised together. The calico has not been tested as far as I know. She got adopted 2 months before I tested the Tiger. Anyway I had the kittens at home with me when we weren't open at the vet. All of them. I have a 1 to 2 year old cat that loves to play but my other cats won't play with him and he loves to play with the kittens. His name is Spooky. Spooky has been around Tiger since Tiger was able to play. I have kept Tiger. No other kittens are here. I did separate Tiger and Spooky for awhile but Tiger didn't like not having a playmate and Spooky didn't like being separated with my other cats and my other cats didn't like Spooky with him because Spooky terrorized them. So neither Tiger nor Spooky were real happy with the situation and I don't want to put Tiger to sleep because he's my little baby and he's not sick. Spooky had been vaccinated for Felv and I tested him about 2 months ago and he was negative and I revaccinated him for Felv. I have now decided to let Spooky and Tiger be together again because at least they are both happy and I don't want Spooky to get Felv but I don't want either cat to be unhappy either so I have let them be together again and they are very happy now. Sorry it took so long to get to my questions but how likely is it that Spooky will get Felv from this kitten (Tiger). Tiger tested a very faint positive and he acts perfectly healthy, he was just neutered 1 week ago and had no problems with the anesthetic. Does having a faint positive result mean Tiger could live longer than strong positives? Also how often can I vaccinate Spooky for felv to improve the chances that he won't get felv. I understand he still could with the vaccine but my vet said that I could vaccinate him every 6 months if I wanted but I didn't know if that would do any good or if it would be harmful or if I could vaccinate him more often or what. Spooky is about 1 1/2 to 2 years old and like I said before he did test negative 2 months ago and he was tested last December when I got him too and was neg. Basically I am just wondering what the usual outcome is of very faint positive felv results, how likely it will be for Spooky to get felv with felv vacc's, and how often can I vaccinate Spooky for felv. Again I'm sorry for the long message. Dawn

Answer: Dawn- I don't think that it matters whether the ELISA FeLV (feline leukemia virus) test is a faint positive or strong positive, just whether it is a true positive or false positive. In this case, I suspect that a false positive test is unlikely but it would be a good idea to do an IFA test. If it is positive, the chance of the result being a false positive is very low. Although adult cats can be infected with FeLV, it is hard to infect an adult cat with feline leukemia virus. It usually takes immunosuppression for some reason, such as the use of corticosteroids, concurrent feline immunodeficiency virus infection or severe illness to overcome the natural resistance to this virus which most adult cats have. I think that once yearly vaccination with feline leukemia virus vaccine is probably more than adequate. Due to the link between feline leukemia vaccination and the vaccine associated sarcomas, I really think that the risk of vaccinating too frequently outweighs the risk of infection with the virus in an adult cat. Spooky is unlikely to become infected but remember that the possibility exists if he has to go on corticosteroids or becomes stressed or ill -- in which case it would be best to separate him until he no longer needs the medication or until he is well again. You do have to be concerned about exposing kittens to Tiger. Kittens less than 4 months of age are most susceptible to FeLV. After reaching 14 months or so of age, natural resistance has usually become strong enough that most cats will not develop FeLV even if exposed to a cat carrying the virus on a regular basis. Keep the kittens physically separated from Tiger to ensure that they do not develop the disease. It would also be a good idea to consider testing any cats that may have come into contact with the kittens you have been raising because it seems somewhat likely that you have a carrier cat they have been exposed to. Kittens can get FeLV virus from their mother, both in the uterus and through infected milk. It is not unusual for entire litters of kittens to gradually test positive over time when they come from an infected mother, so if a littermate of a kitten tests positive it is important to consider the kitten to be potentially infected with the feline leukemia virus. Cats which test persistently positive for FeLV virus usually have shorter lifespans than cats that can clear the virus from their bloodstream and test negative after having a positive test at an earlier time. It could be reassuring to do an IFA test and see if it is positive as well, since there definitely are false positives on ELISA FeLV tests. Hope this helps some. Mike Richards, DVM 11/6/2000

Feline Leukemia and feral cats and Euthanasia

Question: Dear Dr. Richards, I currently volunteer with an organization called Kittico Cat Rescue in Dallas, Texas. About 75% of our work is with the Trap/Neuter/Return program for ferals. Occasionally we will have the need to relocate ferals and we have been fortunate enough to find a feral sanctuary nearby that we can take them to. My problem is this. Recently I have been trapping cats at Lone Star Park which is a horse track in Grand Prairie, Texas. There were 3 adult females, 1male and a litter of kittens. I trapped the first female approximately 1 month ago. She was one of the cats from the momma cat's first litter and she is about 1 year old. We had her spayed and vaccinated and took her to the sanctuary. She's doing great. She has a good appetite and she seems quite healthy. Yesterday, I trapped this cat's sister and took her to be spayed. Only this time, the sanctuary asked that the cat be tested for FeLV/FIV. She came back FeLV+. I have read alot of info on feline leukemia and I guess that I just need some reassurance as to what to do. I know that when I worked for a veterinary practice our protocol was euthanasia for domestics but I have never dealt with the feral situation before. What are the chances that this cat might shed the virus or is that even possible? And when I trap the rest of the cats should we test on a case by case basis? I know how contagious this disease is and I have seen cats suffer with it. I just feel differently in this situation. They were living at a horse racing facility and they were an isolated colony with no new outside cats coming into the group in about a year. They were well fed and had shelter at the facility but management decided that they were a nuisance and must go. If they could stay at the track they would not have to be euthanized after we altered them. All of this is coming from my heart and I guess that I need your medical input to help make this decision easier. Should these cats be euthanized in your opinion? Any input would be greatly appreciated, Apryl

Answer: Apryl- Feline leukemia virus (FeLV) is contagious between cats. At the present time, the feeling is that cats are susceptible to this virus when they are less than a year of age and become very resistant to it after this age. If there is something that compromises the immune system, such as feline immunodeficiency virus, older cats may become susceptible to the virus. Enough stress can probably also make a cat's immune system weak enough to allow infection, which is a conceivable problem in a cat that is fending for itself. My current thinking on FeLV is that there is no reason to euthanize a housecat that lives alone, or lives with other adult cats that it has been with or some time, as long as it is understood that the cat will probably need more medical care than the average cat. The situation is a lot different for an outdoor cat, though. In this circumstance there is a much better chance of the cat passing on the virus to a susceptible kitten or young cat. I think that it is unfair to the general cat population to release cats known to be infected with FeLV virus. Unless a home can be found for these cats in which there is no contact between the colony, I believe that euthanasia is appropriate in this situation. It is hard to be put in the position of having to make this decision but releasing the cat could lead to more than one death among other feral cats. Mike Richards, DVM 6/28/2000

FELV care and lifestyle changes

Question: Dear Dr. Richards: I have a cat named "Baby" and he is a domestic short hair with black and white color. My husband and I found him in front of our apartment about 2 years ago. I think he cannot be more than 2.5-3 years old. He does not like to be hold or carried, so we have never had a chance to take him to the vet. Besides, we had never had a pet before, so we did not know exactly what we had to do. But he has been a very healthy and active cat and never been sick or injured. He likes to stay outside and comes back home to sleep. Last week, both my husband and I had to go on a school field trip for 5 days. We left a window partly opened so that Baby could come in and get out. We left him with enough foods and water for 5 days. When we came back from the trip on 04/04/2000, we found him inside the apartment with a big open wound in his chest. We took him to the Animal Emergency Hospital at once. The doctor said he had been in a fight. The wound was 5" long and deep into the muscles. He had a surgery and also got neutered while he was sedated. The doctor also took a blood test and the result showed Feline Leukemia positive. We were heartbroken. We were told to keep him indoors for life. We took him home that night and took care of him very well. Baby slept through all day all night and seems to be getting a lot better. He eats almost as usual. He is very picky about foods and eats nothing but boiled fish (frozen pollock fillets) and gravy from Fancy Feast sliced beef feast. But just this morning, he really wanted to go outside and was begging us to open the door. We could not stand watching, so we let him out thinking that we could stay close to him and put him back inside after a few minutes. But he run away so quickly. We could not believe that he has that much strength. I know that he will come back home this evening as he always did before. But I worry about him so much since he has the injury. Baby has been in the same neighborhood with same friends since I think he was born. He was little when we found him soon after we moved into our current apartment in July 1998. His friend are all outdoors cats and they all also probably have FELV since baby has it. No one seems to be sick and they all are strong and active. Baby has never been sick too. My questions are .......... - Is it okay for Baby to live the way he has been before since he and his friend have been together for a long time? - What steps I should take to take care of Baby for his FELV? Should I take him to the vet and get treatments now or wait until the symptoms develop? - Should I take another test to see if the first one was right? If so, when and what kind of test I should do it? The first one was blood test. - Can he be still be immune even if he is FELV positive? - Can I get him other vaccinations? - He is strong and healthy even with the injury. Can you tell from the information I give you that he will live long? - I do not care about how much it will cost to get FELV treatments for him. Can you give me information about vets who do this kind of treatments in Austin, Texas area? I apologize for long message, but I thought you should get enough information to help me. Please reply me as soon as possible so that I can do whatever necessary for Baby. The nurse from the Emergency Hospital said there is no treatment for FELV, but from your web I want to believe that there is. I love Baby so much and he is the most important part of my life. Please help me to save Baby. Thank you very much for your time. Sincerely, Thandar

Answer: Thandar- I will try to answer all your questions. If I miss one, or you have a hard time interpreting something, please feel free to write again. - Is it okay for Baby to live the way he has been before since he and his friend have been together for a long time? It is unlikely that Baby will infect his friend, if he has not done so already. However, if he is fighting with other cats, which is likely with this injury, he could potentially infect another cat. This is why your vet recommended keeping him indoors. - What steps I should take to take care of Baby for his FELV? Should I take him to the vet and get treatments now or wait until the symptoms develop? There are no specific treatments that are effective, that I know of, for the feline leukemia virus, itself. When cats have FeLV, though, they are more susceptible to other infections. For this reason, it is necessary to be very vigilant about taking him to the vet at the first sign of illness and treating any illnesses found aggressively. Keep him on a good quality cat food and make sure he is eating every day. Keeping secondary illnesses under control really helps to keep these guys comfortable and to prolong their lifespan. - Should I take another test to see if the first one was right? If so, when and what kind of test I should do it? The first one was blood test. Most veterinary offices test for FeLV using blood tests using a technique known as an Enzyme-Linked Immunosorbent Assay or ELISA test. These tests are very sensitive, meaning they can detect a very small amount of the leukemia virus antigen. However, they do have some false positives, so it is reasonable to recheck the test. We usually try to use a different manufacturer's test but I am not sure that really matters. Then if the second ELISA test is still positive and there is any reason to doubt the diagnosis we will send blood for an immunofluorescent antibody (IFA) test. This test is less sensitive but if it is positive it is very likely that there is circulating feline leukemia virus in the bloodstream. Cats who can not clear the FeLV virus from their bloodstream are carriers of the disease and these cats also have a less favorable prognosis, with an average lifespan of two to five years after infection (varies in different studies). However, much of the time cats with this illness appear to feel well and act like they are not bothered by the disease. - Can he be still be immune even if he is FELV positive? No. If he is positive on two tests more than three weeks apart and/or postive on both ELISA and IFA tests, he is very very likely to really have the virus. - Can I get him other vaccinations? Yes. There is no reason to skip other vaccinations in a feline leukemia positive cat that I am aware of, especially since they may be more susceptible to the illnesses the vaccine protects against. I would think it really important to get at least the rabies vaccination, since he is getting bitten by someone. - He is strong and healthy even with the injury. Can you tell from the information I give you that he will live long? It is not possible to predict the lifespan of a cat infected with FeLV with any precision. The longest lifespan in our practice was for a cat who tested positive on at least four tests from the time he was two until the time he was eleven. He died from lymphoma, a cancer associated with FeLV infection, when he was just short of twelve years old. We have seen cats who appeared to be fine on routine visits who had severe complications of FeLV within weeks. This is just not something that can be predicted with accuracy. - I do not care about how much it will cost to get FELV treatments for him. Can you give me information about vets who do this kind of treatments in Austin, Texas area? Some veterinarians do think that using interferon helps in controlling the secondary problems associated with feline leukemia virus infection. It is probably best to wait until a secondary problem is present to use this therapy since some cats become sensitized to the interferon and then it is not effective for future use. There are vets that use interferon continuously. I have seen this recommendation on the Veterinary Information Network from Dr. Alice Wolf, who is associated with the veterinary college at Texas A&M. Dr Wolf is one of the leading authorities on infectious diseases in cats, so if you don't mind making a trip to see her, you do have an expert on this disease in your state, at least. Baby's current wound should heal fine even with his new excursion. If you watch him closely and provide a good quality environment for him it is likely he could live a good quality life for several years. There is no way to guarantee on that, but he may live longer, too. Mike Richards, DVM 4/10/2000

Sequestered Feleuk

Q: Dear Dr. Richards, I have 2 cats, Truffaut and Fellini. They are both around 11 years old and I have had them since they were kittens. Both were tested (blood test) for Feline Leukemia when I first got them and they tested negative. As they are indoor cats who do not come into contact with any other cats, I didn't have them vaccinated. Now, 11 years later, Truffaut has been diagnosed with Feline Leukemia. We took him in for a blood test because he'd been losing weight and had a few scratches that weren't healing. A blood test showed VERY low white blood cell count and low red blood cell count as well. But the blood test was negative for Feline Leukemia. Then they gave him a bone marrow aspiration and found the leukemia virus hidden there. Fellini has tested negative for leukemia and we are now having him vaccinated. I have a few questions -- one is I don't understand how Truffaut could have caught this. I live in Manhattan in an apartment and he never goes outside. He only has contact with Fellini. My vet thinks he was born with it or caught it from his mother (I adopted him from the ASPCA when he was 5 weeks old.) But how could he have lived with this virus for over 11 years? Second, more important question.... What can I do for Truffaut?? We've been giving him predisone for a few weeks and his white blood cell count dropped even further (from 2000 to 1600 I think). He is also on Baytril. He's acting fine and eating well but the vets are concerned about the low WBC. Is there anything else I can do to help my poor critter? Sorry for the long-winded mail but I'm trying to research this. I've already been through over 2 years of fighting CRF with Fellini and he gets daily sub-q injections... and now I find Truffaut diagnosed with this nightmare. Any advice is GREATLY appreciated. Best wishes, Jacqueline

A: Jacqueline- At the present time feline leukemia virus infection is more confusing than it was in the past (and it has always been confusing). There is a strong possibility that most cats that are infected with this virus have lifelong infections. This is not what we thought occurred even a few years ago. Cats who test negative on blood tests do not have the virus in their bloodstream but it is likely to be sequestered in the bone marrow or in the central nervous system. As long as it stays sequestered it usually doesn't cause much problem. In a small number of cats it seems that FeLV virus sequestered in the bone marrow can cause the bone marrow to quit producing red and/or white blood cells, though. This may be happening in your cat. Immunosuppression is usually attempted in these cases but I do not know how well it works. I worry when white blood cell counts are less than 3000 and the WBC is considered to be critically low when it is below 1000 so there is some cause for worry. It is a good sign that Fellini feels good. I hope that he has continued to feel well and that things are improving now. Mike Richards, DVM 7/1/99

High CPK levels and FeLV

Q: Hello Dr. Mike, I wondering if you could answer a few questions for me? I recently got the results back from a blood panel on my 5 year old FeLV positive cat. My vet was not concerned about the CPK level. He said that he had seen levels this high before and that it could be related to the leukemia, or may not have any significance. The analysis was repeated at the lab for verification and the CPK was 6,962 IU/L as opposed to the reference range of 88 - 382. Is it common to have reading this high, and have you seen any correlations between high CPK levels and FeLV or any other disease? My second question is more of a dilemma. Since I rescue cats in my neighborhood, I have had a sample of many veterinarians in my San Jose, California area. The problem is that it took me years to find a veterinarian that I really liked, and I am now leaving the area of my primary veterinarian. I am moving to the Las Vegas, Nevada area, and am in search of a referral. My primary vet does not know any one in that area and I was wondering if you have a colleague or can recommend someone in that area. Any suggestions? Thanks for your help, Marc

A: Marc- High CPK (creatinine phosphokinase) levels in cats occur for several reasons. There are numerous reports of high CPK levels in the absence of any identifiable disease, too. That may be because of diseases that are hard to find or there may be some problem associated with CPK that we just don't know about. The identified causes of CPK rises in cats are muscle damage, anorexia (not eating), inflammatory bowel disease and pancreatitis (possibly due to intestinal muscle damage, possibly due to not eating associated with these diseases), cardiomyopathy (again due to muscle damage), thromboembolisms (also probably due to muscle damage it causes in rear legs) and a genetic disorder in a research colony of cats with dystrophin deficiency. The CPK value can get into the hundreds of thousands and is commonly in the thousands just from not eating, apparently. This makes it a little hard to figure out how significant a rise in level is. It is still worth looking for any cause of muscle damage, checking for heart murmurs, making sure your cat is eating OK and thinking about pancreatitis. The TLI (trypsin immunoreactivity like) serum levels may be high with pancreatitis and somewhere I think I have read about an increase in pancreatitis in cats with FeLV, so that is another thing you could check out. Monitoring weight over the next month or so would be a good idea, too. As with all testing, lab errors sometimes occur, too. It might not be a bad idea to recheck the CPK level just to see if it remains high. One of my classmates, Roger Paulsen, was in Las Vegas. I can't say that I really know how good a vet he is but he was a very nice person -- one of the nicest in my class. I'm not sure if he is still there and I don't know anyone else. I wish I could help with this one, but unfortunately, I can't. Mike Richards, DVM 4/8/99

FeLV - love and support helps

Q: Dear Dr. Richards, We just found out my daughters cat has fel v. She (Adrina) is 13 and her cat is 10. She is alittle upset but being I volunteer at a local hospice she is very understanding about quality of life and not quantity. We are treating the respiratory infection for now going to take one day at a time. We will let the illness take is own path and make her comfortable as long as we can. She is heavy and still has a great appetite. Any advise for my daughter you would like to share? I'm alittle concerned as she was a foster child before she was adopted and was considered autistic. She has opened up through the years and a lot has to do with her cat. She also started playing the violin 3 years ago and plays wonderfully. The cat hates it though. She wants to spend as much time as possible with her "friend " while she can. Thank you Ginger My daughters name is Adrina, the cat is Stripes

A: Ginger- I wish that I could give you some meaningful advice but it just isn't possible. Ten is a little old for an initial diagnosis of feline leukemia and you didn't say what prompted the diagnosis (what sort of illness is the current problem). However, many cats with feline leukemia can be helped with aggressive therapy directed at whatever secondary problems develop, such as secondary infections, loss of appetite, kidney or liver disease, etc. Keep working with your veterinarian to address the problems that develop and encourage Adrina to provide love and support for Stripes. It really does seem to help. Mike Richards, DVM 2/26/98

Feline Leukemia

Q: Dear doctor, Please HELP! Our cat-cookie-has been with us for about 4 months ( he is about 7 months old). We took him to the vet today for a spay and we found out that he has Feline Leukemia. The local vet says it is acute. We have been away for the last two weeks and when we picked her up yesterday, the changes were significant. He has lost weight, he is not eating and he seems very tired and lethargic. The vets tech pointed out extremely white gums and indicated he was anemic. They seemed pretty nonchalant about the whole process and immediately wanted to put him to sleep. This cat is my nine year old's very best friend. I can not do this without being certain that I have done everything I can to help. The doctor has intimated that our cat will not live more than a few weeks. I can not believe that in this day and age that there is not a thing I can do for this cat. I have receive antibiotics to be given to her BID. Predisone tablets once daily and special A & D cat food with a syringe. I am willing to force feed him if I have to and if it will help. PLEASE write back as soon as possible if you can give me any advice. I am doing the right thing? Do it sound hopeless? I realize that there is only so much you can do from afar, but is there anything I can do to prolong his life WITHOUT pain and suffering (or at least minimal suffering). Is it typical for cats to die as early as 7 months from this disease? THANK YOU so much Paula

A: Paula- It is not unusual to see young cats who are severely ill due to feline leukemia virus infection. Supportive care is all that can be done. Antibiotics to prevent secondary infections and prednisone to suppress the white blood cells are the most common treatments. Anemia may need to be corrected with blood transfusions and other supportive care may also be necessary. There is not always a positive response to treatment even with aggressive care. I hope that your cat did respond and is doing better by now. It is not unusual for veterinarians to be discouraged about treating for feline leukemia virus when there are severe clinical signs. It is hard to recommend intensive and costly treatment in the face of an illness that is often non-responsive. But your wishes are the most important part of the equation and if you wish to try your vet should, and almost certain will, respect that wish. Mike Richards, DVM 2/16/99

Feline Leukemia

Q: What are the symptoms of feline leukemia? My cat is an inside cat and has been since the day I found her 6 yrs ago. At that time she was tested and had all her shots. I have not taken her back to the vet since because she never, ever, goes outside. Lately, (last 2 wks) she has been throwing up after she eats, and she occasionally sneezes. Could it be Feline leukemia or do cats get the flu or colds? Thank you for any advise. Vickie

A: Vickie- In general, almost any clinical sign of illness can be related to feline leukemia virus so it is a concern in any ill cat. Vomiting is not the most common sign and your cat's history is not highly suggestive of this disease but it would be best to have your cat checked by your vet to find out what is going on. Mike Richards, DVM 2/16/99

FeLV related problems

Q: Dear Dr. Mike My husband and I have had Elmo since he was a small kittem (3 weeks) His mother was killed and we had to hand feed him. Anyway he tested positive for FeLV from the very beginning. The docter said it was a faint positive and he might "fight it off" We had him tested again 2 months later and again the vet said that it was a faint positive. I have some questions related to this. He is now 1yr 1/2 old and is very aggressive ( i.e biting , pouncing) and is skiddish around strangers. Is this related to FeLV or being weaned so early? Also would it be OK for us to someday get a dog? we have always wanted to adopt a Greyhound and would like some suggestions concerning this. Finally what symptoms should I look for to see if he is developing an illness related to FeLV? Thank you so much for your time and answers!! Elmo's mom

A: Shannon- It might be worthwhile to consider testing Elmo with a different test method but it is probably likely that he is persistently infected with FeLV. He poses no risk to a dog and a dog poses no real risk to him except perhaps by increasing the stress level in his life. It is not unusual for cats who are weaned early to be overly aggressive while playing, so that is the more likely problem with that behavior. It is often possible to teach cats limits to biting/playing behavior even later in life so you might want to ask your vet to help with suggestions for this ( I think we have some on our web site, too). FeLV can cause lots of symptoms. The best approach is to take Elmo to your vet as soon as you notice any difference in his behavior, eating habits or anything that makes you think he might be ill. Early aggressive treatment of problems secondary to FeLV helps to prolong a cat's life that has feline leukemia virus better than anything else. Mike Richards, DVM 1/99

Adding another FeLV positive cat

Q: We currently have a male cat that is about 3 years old. He was a stray that we took in about a year ago, He tested positive twice for feline leukemia. We would like to get him a playmate (another cat). I understand that if we are to get another cat, we should get another one that has also tested positive. My concern is that so far Indy has had no medical problems, and is in perfect health. So I assume his virus is currently latent. If we were to get another cat, that may not be latent or may develop medical problems sooner, are we putting Indy's health at risk. Is there any possibility of an active carrier with active disease making Indy's disease become active sooner than it would otherwise? I don't want to get another feline positive cat if the contact could increase Indy's medical risks. Sincerely, Brenda

A: Brenda- If your cat is still positive for feline leukemia (which he probably is if he tested positive twice) then it is unlikely that his status will be affected by the addition of another cat, unless he finds that situation stressful, or the new cat carries another disease he has not been exposed to or if there are fights that lead to injury and bacterial infection. Since those things are possible it is a good idea to weigh the decision to add a new cat carefully. Do quarantine the new cat so that any transient illnesses that might be stirred up by the stress of a new home pass before the cats are introduced. Many people do adopt new feline leukemia positive cats in this sort of circumstance quite successfully. Mike Richards, DVM 1/99

Feline Leukemia Diet

Q: My cat was diagnosed with Leukemia. What type of diet she should be on? Are there any foods that are best for her to eat? Thank You Lara

A: Lara- At present the best recommendation that I can make is to feed her a high quality diet to ensure that she is getting adequate energy from the diet. Canned food is probably a little better in this instance than dry food because it tends to have more fat and less carbohydrate (at least I think that is the case), which is actually probably better for a pet with cancer. Recently Hill's came out with a prescription diet for dogs with some types of cancer but I don't think there was a cat version of this diet. Iams also has a diet formulated for helping cancer patients but I do not know if they have a cat version, either. Mike Richards, DVM

FeLV positive kitten

Q: I just acquired a kitten (Winston) who tested positive for FeLV. I was heartbroken-as were my two children. The person we got Winston from had the brother as well. The brother tested positive "with a trace". We decided to take the brother in as well, because the women who took the cats in had an older cat that she didn't want to expose to the disease. Here are my questions: 1) Can I provide some sort of vitamins for my kittens to help keep them as healthy as possible? Currently they show no symptoms, and if I can do anything to keep them that way, as long as it's not outrageously expensive, I'd like to do it. What is Interferon? 2) My vet never suggested to have Winston (or his brother) re-tested. I was never told what type of test was given to him, never given any options on treatments, never really provided with any sort of information. Should I ask to have them both tested again? And finally, as mentioned above, I have two children (7 and 9) who adore the kittens. I have explained to them that the kittens have this virus, and that they may not live a very long time. They seem to have accepted this (after a bit of crying), but want the kittens around as long as they are healthy. Do the kittens pose any risk to my kids? The vet said "no" but I did read with much concern the same question about the British study that talked about increased risk of leukemia with children that had cats. Are there indeed studies on families that have FeLV+ kittens with kids? And are indeed the kids fine? I think I need some reassurance here. Thank you so much! Carolyn

A: Dear Carolyn- I think that you should have the kittens retested. If the second test comes back negative there is a very good chance that the kittens will live much longer than if the second test is positive. Since I have delayed in responding to this question it has been long enough to retest them at any time. If the second test is positive the average lifespan is shorter but can still be of good quality for several years. I do not know if any vitamin preparations are helpful in extending longevity. It is a good idea to be sure that vitamin requirements are met but most good quality cat foods do meet the minimum requirements. Interferon is an immune system modulator that some vets believe is helpful in prolong the quality and/or quantity of life in cats infected with feline leukemia virus. I do not have an opinion either way on this but it seems to be pretty safe. There have been a number of studies which have shown no relationship between feline leukemia infection in cats in a household and leukemia or lymphoma cancers in humans. There have apparently been two reviews of the infection rate in infants or young children which showed a higher rate of leukemia in households with a feline leukemia positive cats, one of which was from Britain. I am not familiar with these studies but they are mentioned in Dr. Scherding's book "The Cat, Diseases and Clinical Management". It is my impression that the consensus of opinion among oncologists is that this link is very tenuous or that it doesn't really exist. I would personally feel comfortable having a feline leukemia positive cat in my household but everyone has different levels of comfort or tolerance for risk and you have to do what seems right to you. If I can find these studies I will try to post an abstract online. Mike Richards, DVM


Q: Hi Dr Mike, I have a few questions, mostly related to FeLV: I have a cat that tested FeLV positive, a few months later I had her retested and she tested negative. The first test was sent to the lab (they said they tested it twice at the lab). When I had her retested, she had an IFA test (which was sent to the lab) and an in-house elisa test -- both were negative. Someone told me that if a cat tests positive (excluding false positives) and then later tests negative, the cat doesn't really seroconvert, it just sequesters the virus in the bone marrow and it can resurface if the immune system is later compromised. Is this true??? I have a FeLV positive male cat that was forming acidic crystals and stones in his bladder. About two years ago he was on a cat food made by Flint River Ranch (a high quality oven baked kibble that is made from human grade meat). He was on this food for a few years and was also receiving sodium ascorbate. We discontinued the sodium ascorbate, but he was still straining when he urinated. I tried to find other diets without acidifiers, but they all seemed to have DL -Methionine. I switched to Eukanuba chicken and rice and he stopped straining. About a month later I tried the Flint River Ranch diet again. About a week or so later, he started to strain again. He has been on the Eukanuba for the last two years without any problems. I still feed Flint River Ranch to my other cats and have had no problems with them. Is there any connection between acidic crystal formation and FeLV? I have other concerns about the use of these diets. I am pleased with both diets, although both diets are high in protein and fat. I was told that the high protein and fat content would "blow out their kidneys at an early age". I was also told by someone else that it is not the the protein or fat content that is damaging, but the source of the fat or protein. So, if the source of protein and fat is from "real" meat, is it okay to have a high fat and protein content?? Thanks, Marc

A: Marc- I don't think that anyone knows the answer to your first question at the present time. For a long time veterinarians assumed that cats had three outcomes from the initial infection with feline leukemia. 1) they died from the initial infection 2) they became carriers of the disease until they became ill from it and died 3) they became immune. Recently it was proven that cats could sequester the virus in their bone marrow or central nervous system, keeping it suppressed indefinitely, perhaps lifelong. In the event of a serious illness or immunosuppression for other reasons such as corticosteroid administration, some of these cats lose the ability to suppress the virus and it becomes an active problem again. The question is this: do any cats become immune or are there only cats who are infected but suppressing the virus effectively in this group? My guess is that there are many more cats suppressing the virus than there are cats who are able to become immune. So it would be worthwhile to test your kitten anytime that there is a serious illness, unfortunately. I am confused by your second question and this confusion is actually the reason for the delay in responding to your inquiry. This is what confuses me: acidic urine is associated with the production of calcium oxalate stones in cats but the treatment you are describing actually sounds like the treatment for struvite crystals which occur more commonly under natural conditions and which are treated by acidifying the diet and restricting magnesium. Sodium ascorbate is Vitamin C or at least closely related to it. Administration of Vitamin C will acidify the urine, but not usually efficiently enough to help a whole lot with struvite crystals. It would almost certainly encourage the production of calcium oxalate crystals. D-l methionine is commonly added to cat foods to acidify the urine in an effort to cause urinary acidification. It works pretty well for this. Most cat foods strive for a neutral pH or slight acidification. I have no idea what effect the Flint River Ranch food has on urine pH. Eukanuba is supposed to slightly acidify the urine. Given this, I would tend to think that your cat has struvite crystals and that urinary acidification is helpful rather than harmful. If I am wrong and these were calcium oxalate crystals, then it would be better to try to find a food that causes a more neutral pH. Hill's makes a food specifically for cats with calcium oxalate stone problems and other "ordinary" foods produce neutral urine. I do not know of an association between feline leukemia virus infection and feline lower urinary tract disorders but one is possible. High fat diets are not particularly harmful in cats unless they are overfed, leading to weight gain. The same is true for high protein diets. I do not know of any benefit to feeding high fat or higher than needed protein levels, though. If you have the same confused feeling about the acidic urinary crystals as I have it may be a good idea to discuss this with your vet and try to figure out whether there has been a miscommunication or if these were in fact calcium oxalate crystals. Mike Richards, DVM

Feline Leukemia Kitten

Q: Dr. Richards, I don' t know where to start --- my kitten, who is almost three months old was diagnosed with FeLV three days ago. My husband and I had just gotten her and were taking her in for her initial vet exam. We do not know if she got it from her mother or from another cat she was with. We are so confused and keep getting conflicting information. We do not want to put her down - she is healthy at this time. We feel so helpless though. I guess my first question is this - a) as a kitten with it, is it possible for her to be healthy? It seems to me that a kittens immune system would already be weaker than an adults cats and therefore it be at a disadvantage with this virus. b) have there been any cases where a kitten (whether getting it from another cat or in the womb) has been able to pass this virus out of their system? I know that there are no simple answers - I'm just scared for our kitten and want to keep her healthy as long as possible --- (do you recommend vitamins? or foods with vitamins (I don't want to stress her out by making her take pills at this time...) I don't think we are alone in our crusade and our desire to keep her around. These are just the beginning questions - tons more are swarming around. Thank you so much for reading and responding to this. Please let me know where I can turn for info. -- It's scary being ignorant. Many thanks - Sean and Karla

A: S- Some kittens are able to clear the virus from their system. Others are able to suppress it sufficiently that they are not affected by the virus and do not transmit it to other cats. The exact percentage of cats able to do one of these two things is not known exactly but it probably is at least 30% and may be as high as 50% or more of infected kittens. Kittens that remain positive for the virus on two or more tests done at 3 to 6 week intervals are likely to remain positive. These kittens often have several years of relatively normal life and then develop problems associated with the feline leukemia infection. In some cases there is severe illness early in the infection, though. These kittens are also potentially infective to other cats and need to be kept isolated from other cats who are not also positive for the feline leukemia virus. As long as this is possible I see no reason not to try to provide a good life for a cat infected with the feline leukemia virus. You are correct in the assumption that kittens are at a disadvantage when infected with this virus. Feline leukemia virus infects kittens much more readily than it does adult cats. Most cats that are infected with this virus probably were infected as kittens. Even so, there are a number of kittens who can suppress the virus. I hope that your kitten is one of the lucky ones. If not, you can still provide her with a good quality of life, potentially for several years. It means being responsible for her and not allowing her to have contact with cats or kittens who might become infected but that usually isn't too difficult to accomplish. Mike Richards, DVM 3/99

FeLV transmission

Q: Dear Dr. Richards, My name is Veronica A and yesterday my cat was diagnosed with FeLV. I found this cat in the woods about 3 weeks ago, and was told the cat was about 5 months old. My cat, Oliver is scheduled for a retest in October. I also have 2 other cats in my home, but my question is, is it safe to have Oliver living in my home upstairs, while I have my other 2 cats living downstairs and outdoors? Is there still a chance that my 2 other cats can still get infected? Should I wait for the retest before making any decisions? Please let me know what you think. I would really appreciate it. Thank You , Veronica

A: Veronica- Feline leukemia virus is transmitted by contact with bodily fluids from one cat to another. The virus does not live more than a few seconds in the environment, so it is generally considered to be safe to keep a cat with feline leukemia if it can be kept physically separated from other cats in the household. In addition, feline leukemia virus is most easily transmitted from an infected cat to a kitten and natural immunity to the virus appears to be pretty strong in adult cats. Since you have an inside/outside cat I am presuming that the other cats are also vaccinated against this disease, making it less likely that they would be infected as well. With all of these things going for your downstairs cats I really think it is probably safe to keep Charlie upstairs and separate from them without worrying too much about the other cats contracting feline leukemia virus. It is a good idea to retest, after at least a three to six week interval, whenever a cat tests positive for feline leukemia virus. Many cats can either free themselves of the virus or suppress it sufficiently that they do not pose a threat to other cats. In either case, the test should be negative on the second test. If the cat continues to test positive on two tests this far apart if may be a good idea to test using another testing method or to assume that the cat is infected and capable of transmitting the virus, in which case it should be kept separate from other cats. Hope this turns out well on the second test. Mike Richards, DVM

FeLV survival

Q: Hi, I'm a vet tech and I have a cat that is almost 2 years old. She has been positive since she was a kitten. She isn't really showing any signs of the virus and never has. Just a runny eye and she had swollen glands that we treated with pred. when she was about 4 months old, which never reoccurred. What I'd like to know is if there are a lot of positive kittens that have done as well as mine or if she is an exception. I've had her on interferon since she tested positive. At first I also had her on vitamins (she was malnourished). Thank you for any information you can give. Vicki

A: Dear Vicki I am only aware of one study that reported lifespan expectations for cats infected with feline leukemia virus and persistently viremic (continuously test positive). In the study, reported by Dr. Susan Cotter in the November 1991 issue of the Journal of the AVMA, most cats died within two years but about 20% of the cats lived three or more years. In our practice we had one cat who tested positive at 2, 4, 7 and 11 years of age and lived a fairly normal life until he was eleven. I can't remember another cat that did nearly that well, though. I think that cats who live alone or with one other cat do better than cats in larger households, probably just because they are less exposed to other diseases and less stressed. Cats who can not clear the feline leukemia virus (FeLV) from their bloodstream need to be carefully monitored. If they show signs of illness they should be treated promptly and aggressively. It is not a good idea to adopt a "wait and see" attitude about any illness in an FeLV positive cat. Ensure that your cat has a good quality diet. Checking the mucosal color (gum color, conjunctival color) on a regular basis and occasionally having bloodwork drawn to ensure that anemia is not a problem may be a good idea. Interferon is used by many veterinarians and most feel that it helps. I do not think that the scientific literature adequately proves that interferon use is helpful, though. It does appear to be very safe and I see no reason not to try it. An FeLV positive cat should be kept indoors. The virus infects kittens much more effectively than adult cats. You should not bring a kitten home to live with this cat. For some people this is very hard but it is important. I hope your cat continues to do well. Mike Richards, DVM

Feline Leukemia and children Q: I have friend with cat with feline leukemia....her vet said there was an increased incidence of leukemia in children where cats with this disease were around? is this true???? never heard of it and can't imagine it lives long enough to cause problems in humans... Thanks, BMan

A: BMan- There was an exchange in the letters to the editor (I think that is where it occurred) section of a veterinary journal in which this claim was made. It was apparently based on a British study in which children with leukemia were studied for factors that might have contributed to their disease. Children with cats were more likely to have leukemia in that study but to the best of my knowledge (I have only seen reference to this in a textbook, not the article) there was no mention of this being from feline leukemia virus. Many other studies have been done since this one and none have shown any evidence that feline leukemia virus can cause leukemia or lymphoma in humans. I truly believe that this information is simply incorrect. Mike Richards, DVM

Feline leukemia transmission and false positive test


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...