Cancer and Tumors - Mast Cell Tumors


Mast cell tumors in Golden - what about vitamin C in massive doses

Question: I have a 10 year-old golden retriever with a history of mast cell tumors. AT age 6 he had a mast cell carcinoma removed from his paw, followed by 5 weeks of radiation treatment at the U Tennessee Vet School. Last month we removed another similar tumor from the web on his rear paw. Aspiration of the lymph glands in the groin area indicated mast cells-- not cancerous but described as "tweener" by the pathologist. The suggested treatment is massive doses of vitamin C. What can you tell me about this treatment, or direct me to some references. Thank you. WF Answer: WF- I have not been able to find the literature reference for this use, but there was reported to be a study which showed that Vitamin C, "in vitro" -- or in the laboratory, could aid in the therapy of mast cell tumors with chemotherapeutic agents by helping overcome resistance to them. There was some question about whether comparable dosages of Vitamin C could be achieved in a patient, though. I am not aware of its use as a sole chemotherapeutic agent but can't say that there hasn't been some research on this that I am just not aware of. I am still under the impression that radiation therapy in conjunction with surgery is the best approach to controlling these tumors and that some of the newer chemotherapeutic agents are showing some promise, especially vinblastine and CCNU (Lomustine Rx). I am sorry that I can not supply more specific information on the use of Vitamin C. Mike Richards, DVM 2/22/2001

Mast cell tumor in Golden Retriever

Question: Dear Dr. Mike: My dog Shelley (almost 7 golden retriever) has been diagnosed with Mast Cell Tumor (Grade II, Clean Edges). The tumor was excised completely, or so we hope. Tests for staging will be done in the next week or so because we want to give her some time to recover from the excision surgery as well as an ear hematoma surgery that happened at the same time. I'd like your opinion on treatment options for Shelley. And prognosis for survival. She's like our child and we want to make sure that she gets the best possible treatment. We will be consulting a vet oncologist but plan to do that only after the staging results are available. Thanks in advance for you help. SK Answer: SK- In a review of mast cell tumors from 1988 (Vet Med, Paul Dean, 2/88), 44% of dogs with Grade II mast cell tumors survived more than 1500 days after surgical removal of the tumors, without additional treatment. A paper from the Animal Medical Center in Manhattan (Saraff, et al, 1996), of radiation therapy for the treatment of grade 2 mast cell tumors in 32 dogs with Grade 2 tumors of the skin, had a better prognosis, with 86% of dogs treated with surgery and radiation making it to five years post treatment. Based on this, it seems like a good idea to consider radiation therapy, even when clean margins are obtained during surgical excision. Chemotherapy is an option but does not seem to be as effective as radiation therapy. However, radiation therapy is not as effective if the tumor has spread (Stage 2 or greater) --- so in this case, chemotherapy may have an edge. The oncologist will be able to help you decide which approach will be best for Shelley. I really think that you are taking the best course of action seeking a consultation with an oncologist. I hope all goes well with the staging. Mike Richards, DVM 7/9/2000

Mast cell tumor - grading and staging - the ways tumors are classified

Question : Hello Dr. Richards, I read through the Dogs/Cancer section, which was very informative, but I still have a couple of questions for you. I have an 8 month old, fixed (he was fixed at 6 months), male pug named Odie. He's healthy in every way except about 2-3 months ago I noticed a growth on his foot, it didn't seem to bother him so I didn't really think too much of it, but kept an eye on it. It didn't get any bigger but it didn't go away either so I brought him to the vet & we decided to have it removed. The growth was no more than 1/4 of a cm & the vet removed a considerable amount of skin around the growth. We just got the pathology back on Monday & the vet explained that the growth was a stage 1 mast cell tumor. The tissue around the tumor was free of cancer cells. I'm concerned that because of the location of the tumor, not enough tissue below it was removed, the tumor was in a location equivalent to the top of a human's foot. My questions are: -How serious is a stage one mast cell tumor? (would it be possible to compare it with a cancer in human's such as melanoma?) -Should we have the vet do bloodwork, lymph node aspirate, or abdom. ultrasound to make sure the cancer hasn't spread? (bloodwork done 2 months ago, when he was fixed, was normal) -What type of follow up should we be doing? (bloodwork, etc.) -Would it be wise to have Odie on Prednisone? or would that weaken it's effectiveness in the case of possible future tumors? -Because of the location of the tumor & the results of the pathology, do you feel enough tissue was removed or should we have more tissue removed below the area of the tumor? -Should we be more concerned about the tumor because of Odie's age (we noticed the growth when he was 5-6 months old)? -Is there any information on reoccurrence of stage 1 mast cell tumors? Could this be a one-time thing? -Should we consult with an oncologist? -What do these tumors usually look like (on the skin)? I realize I've asked a lot of questions, I'm very concerned about the health of my dog! We love him soo much. I also feel that the questions I've asked could be of help to others. I sincerely appreciate any information you can give me on the above & any other websites/books I could look at for more information. THANK YOU!!! Sincerely, Angela Answer: Angela- Tumors are classified in two ways. Staging is a way of classifying how far a malignant tumor has spread prior to diagnosis. Grading is a way for the pathologist to give his or her impression of how aggressive a tumor is likely to be (how likely it is to try to spread to other tissues). There are different staging schemes, but the standard is probably the World Health Organization staging, even though it is geared more towards humans. A slightly simplified version of this is: Stage 1 -- tumor is solitary, no sign that it has spread, tissue margins are clean on removal Stage 2--- the tumor has invaded regional lymph nodes Stage 3--- the tumor is widely invasive (invaded past surgical excision) or there are multiple tumors, even if the lymph nodes are not involved Stage 4-- the tumor has invaded tissue far from the original site, such as the spleen, in the case of a skin tumor Staging is done by your veterinarian. Physical exam findings, X-rays, bone marrow examination, complete white blood cell counts, buffy coat smears (the buffy coat is where white blood cells accumulate when blood is centrifuged in a tube) and lymph node aspirates may all be useful in staging mast cell tumors. You should be sure that some attempt is made to stage this tumor accurately. Grading is somewhat subjective and is partially the pathologist's opinion, although there are guidelines for grading, too. Grade 1 tumors are the least likely to be highly malignant and Grade 3 are the most likely to be malignant. The problem with a tumor located on the foot or lower limbs is the difficulty removing enough tissue under the tumor, just as you mentioned. It is reassuring that the section of the tumor the pathologist examined had no tumor cells beyond the margins but unless it was possible for the pathologist to accurately judge all sections of the tumor that might have had contact with surrounding tissue it is hard to be sure that this assessment applies to the entire tumor margin. The prognosis for a Grade 1, Stage 1 mast cell tumor responding completely to surgical excision is good. Around 90% of dogs are reported to have long term survival after this diagnosis in most of the studies done on mast cell tumors. This has to be considered in your decision making but there is some room to worry and I would think it would be a good idea to ask your vet to refer Odie to an oncologist or to at least consult with an oncologist about what to do next. There is a lot of ongoing work on chemotherapy for mast cell tumors and radiation therapy can be helpful in cases in which it is questionable whether adequate tissue could be removed from underneath a tumor. Prednisone is variable in its effects on prognosis following mast cell tumors, with positive responses seeming to run about 20%. Due to Odie's age I would tend to lean towards doing some other sort of follow-up treatment but your vet or the oncologist may have another opinion on that. Mast cell tumors are very variable in appearance. They are tumor most often used to illustrate why it is possible to justify having almost any skin tumor examined by a pathologist. I am not aware of any prognostic factors that hinge just on the age of the patient. I think that staging and grading are the most reliable indicators of prognosis. Hope this helps some. Mike Richards, DVM 6/23/ 2000

Mast cell tumors in Labrador

Question: My 10 year old Lab has two visible mast cell tumors. At this time treatment consists of pred and antihistamines. The largest tumor is considered inoperable due to location, and also because of other health problems this dog has (non life threatening, but not life enhancing) it is not anyone's wish to put her under anesthesia. My question is that I cannot get a clear understanding as to how aggressive these tumors are. I have had one doctor say very aggressive, one seem not to concerned, and Ettinger's Vet. Internal Med. gives me lots of great information, but not much on how rapidly this can spread. Could be my denial keeping me from reading the answer I don't really want, but what would you say? Thank you, N Answer: I have been trying to find information for you on mast cell tumors treated with prednisone alone and the prognosis for these tumors. All of the information on prognosis that I can find relates to mast cell tumors which were removed surgically and then treated with various forms of chemotherapy, including prednisone.

Mast cell tumors are variable in how they affect dogs and in how long it takes for them to cause significant problems, though. We have had several patients in which we positively identified their tumor type as a mast cell tumor and then owners declined therapy. My best recollection of these cases is that most of the dogs lived for 1 to 2 years, one lived for several years and at least a couple developed pretty severe clinical signs relating to the mast cell tumors very quickly. So I suspect that your vets are probably accurately relating their particular experiences with this tumor with perhaps a small amount of their basic tendency towards optimism or pessimism mixed in. Mast cell tumors can cause gastric ulcers and GI upset prior to that time, so it is a good idea to use a medication like cimetidine (Tagamet Rx) or famotidine (Pepcid AC Rx) in addition to prednisone. There are other chemotherapy agents that might be helpful if you wish to pursue chemotherapy without surgery. Radiation therapy can also be helpful but it doesn't sound like that is likely to be a good alterative, either, if surgery isn't possible due to other health problems. I wish that I could give you a more specific answer but just based on our experiences I think that most dogs probably experience complications from these tumors within a year and that complications severe enough to cause consideration of euthanasia usually occurs within 2 years. I hope that your Lab does better than this. Mike Richards, DVM 6/5/2000

Cairn with possible mast cell tumors

Question: I read all I could on your site in regards to mast cells and skin tumors. I found your site today while wandering around -- I took my baby, Dusty, to the vet today because I thought that she had a tick on her nose -- but found out that it wasn't and that it could be a mast cell. I think that the vet was trying to be kind and keep me from over-reacting and said that it could be a cyst, but now I recall that the word "mast cell" came up several times and he said that histiocytomas which are usually benign occur in younger dogs. After reading your articles, I am really scared (not your fault, just me). He aspirated the tumor today and told me that he will try to get information as soon as possible..... She is ten years old and has had one adrenal gland removed because of a benign adrenal tumor which caused Cushings. I read about another dog on your website that had a similar history - does Cushings' predispose dogs to this disease? I understand that surgery is best -- but is the surgery you described possible on her nose? It is right above the black part of her nose -- it just popped up almost over night! Just the thought of her having surgery makes me crazy -- she almost died when they removed her adrenal gland.... You answered one person and said that they should ask about the stage of the disease -- is there anything else that I should ask about? She has been having problems eating lately -- is this part of the history? This vet seems pretty good -- but IF she has this, should I get a second opinion? Is there anywhere else that I can read about this? C.

Answer: C.- I am not aware of a link between Cushing's disease and mast cell tumors and couldn't find anything in the literature to suggest one. So I think there isn't much worry there. It is very hard to identify mast cell tumors based on appearance alone. Most of the time when I think a lump or sore is a mast cell tumor it isn't and several times I have been certain I was removing a benign little lump that turned out to be a mast cell tumor when examined by the pathologist. It is very hard to wait for pathology reports and I know it is impossible not to worry while waiting -- but it really is non-productive. But if this does turn out to be a mast cell tumor it is definitely possible to remove enough tissue around it, even on a nose, if desired. The problem with locations like this is that surgeons who do not routinely treat cancer cases tend not to be willing to take enough tissue. So it is best to ask for referral to a surgeon who works with an oncologist, or is an oncologist as well as a surgeon, if possible. If necessary, it is possible to combine surgery with radiation therapy or chemotherapy, too. These surgeries pose less surgical risk than removing an adrenal gland. I am going to hope that your worry will be unnecessary. I honestly think the odds favor that assumption. But if this does turn out to be a mast cell tumor there is still a reasonable chance for a successful outcome. Mike Richards, DVM 11/21/99

Tumor removal

Question: i got interested in vetinfo when i found out our little terrier mix dog, millie (we have two dogs), had a mast cell tumor on her chest that was malignant. the oncologist performed biopsies on her blood, spleen and bone marrow and took x-rays. all of the tests came back clear, but she (the oncologist) said she would like to go back in to make sure the area was clean. she may have forgotten to prepare me for the second surgery (the first surgery and removal of the tumor was performed by her regular vet), but when i went to pick her up a few days ago, her original incision area, which was probably 1.5 inches, was now about 6 inches. of course, with the combination of learning the cost, seeing the second incision and having her truly keen all the way home, i was a mess. she has subsequently perked up and we are happy once again, although i haven't heard the results of the new biopsy as yet. my question is do you think this seemingly very radical procedure is the norm in treating mast cell tumors? i inferred from your website that they are very aggressive. thanks very much for caring and look forward to hearing from you! judy Answer: Judy- At the present time a new definition for cancer surgery has evolved. Usually this is described as "with acceptable tissue removal to satisfy oncological principles". This basically means taking at least 2cm of tissue (and cautious oncologists say 3cm) from around the tumor site IN EVERY DIRECTION. This last bit is really important, because almost all general practitioner vets want to cheat on that margin in at least one direction. Two centimeters is about an inch. Removing tissue to the depth of an inch below a tumor often involves removing underlying bone, something almost every general practitioner is loathe to do. It also means making an oval incision that is at least 6cm in length in almost every case, because incisions have to be about 2.5 to 3 times as long as the width of the removed tissue in order for the edges to go back together in a straight line. So the oncologist has followed the current guidelines for cancer surgery. There is no totally effective chemotherapy for mast cell tumors. Radiation therapy as an adjunct to surgery seems to help in some cases but it is expensive and it is also not 100% effective in eliminating metastasis of the tumor to new site. Whether or not radiation is necessary as a follow-up depends on your willingness to do it and the oncologist's opinion as to its value, which would be based at least in part on the examination of the margins of the tissue removed in the second surgery. There really isn't a good excuse for you not knowing just how radical the surgery was expected to be, unless for some reason you were told and it just didn't sink in because it is one of those things you can hear without really being able to imagine (I have those kinds of mental blocks for some things). Specialists are like vacations -- they almost always cost more than your general practitioner vet thinks they will when he or she refers you and more than you are expecting. On the other hand, they usually do a thorough job and they have the outlook and experience to do things like really taking the necessary surgical margins. You were right to allow this aggressive approach in order to give Millie the best possible shot at full recovery. I hope that it works well for her and for you. Mike Richards, DVM 1/2/2000

Mast Cell Tumor

Question: Dear Dr Mike, I have just registered as a subscriber to your superb site. Coco is a four-year old, spayed bitch. An extraordinary creature who was abandoned in a ditch as a pup. She (along with Daisy, also abandoned and close to execution when we rescued her) light up our lives. Hong Kong is not, in general, a place where animals would choose to live. About 18 months ago, Coco developed what was diagnosed (in Italy) as a MCT. Your site proved an invaluable source of information (and comfort) during this rather stressful period. The Italian vets aspirated the tumour, and when the histology and other tests confirmed a Grade 1 MCT, determined to excise it in the radical manner you describe. It was very well differentiated and had not spread to surrounding tissue or bone marrow. She is a nervous dog who did not enjoy the experience. The removal of bone marrow was especially unpleasant. Fortunately she recovered quickly and, before long, all traces of the surgery had all but disappeared. About six months later, however, we noticed a similar swelling - in a different place. Exasperated, we went through the whole process again. The circumstances were almost identical" another MCT Grade 1. And again our (excellent) Italian vets removed it and much of the surrounding tissue. They also put her on a fairly high dose of prednisone (25 mg per day for about a month, tapering down gradually to 5 mg per day). She has been off the cortisone for about a month. It seemed to have caused rather serious urinary incontinence which continues in a milder (but still upsetting) form: trickles of urine (which she feverishly licks) almost every night, though never, it appears, during the day. Notwithstanding all this, Coco has, thank goodness, resumed her normal ebullient personality, though retains a deep fear of vets and even of anyone who seems to be examining her - including me! About 10 days ago, I noticed that what I thought was one of her nipples seemed hard and dark. I left it alone, but it grew a little larger, resembling a mole on a human. I rang our vet (we are now back in HK) who thought, given her history, it could be another MCT. But he suggested (since it was a holiday) that it could be a tick. I decided, despite Coco' nervousness, to inspect it closely and it did rather look like a tick. Using my favoured method (gin on a tissue) I attempted to pull it off. What came away looked like a scab, rather than a tick. Despite its removal, by the next day it had returned, and it now appears almost exactly as it did before. It doesn't bother her in the least, but, after consulting your Vetinfo and other sources, I am flummoxed. What is it?? It doesn't resemble in any way the two MCTs. I can, of course, take her to our (new) vet, but I would greatly value your responses to two questions: * What could this latest lesion be? It is either on or very close to one of her teats * * Is the urinary incontinence likely to pass? If not, what do you recommend? * Many thanks for your help. Keep up the admirable work! R.W. Answer: R.W. It is not possible to totally rule out a mast cell tumor as the cause of the nipple irritation/scabbiness due to Coco's history. However, there are a number of dogs that develop irritations with scabbiness or accumulation of sebaceous "junk" around nipples and most of these are not cancerous. They seem to be most frequent in dogs with skin folds around the nipples or with nipples that are sort of inverted but they can occur even in normal appearing nipples. I am not sure what causes these lesions but most of the time the dogs are contributing somewhat to the inflammation by chewing or licking around the nipple. Cleansing these with a benzoyl peroxide shampoo twice a week until healed has helped in some cases, antibiotics have helped in others and we have had to remove the nipple and surrounding skin on occasion in order to resolve the problem. Usually we only go that far when they become infected or the inflammation seems painful. If Coco is nervous enough about medical procedures that she won't allow you to cleanse the nipple it may be that you will have to think about surgery as an option if the problem persists or worsens --- and it does give you the opportunity to have the lesion examined by a pathologist to be sure it isn't a recurrence of the mast cell tumor. Prednisone usually doesn't cause incontinence in dogs that are not already prone to it -- but it definitely can bring on symptoms in these dogs and sometimes they do persist. Incontinence is usually treatable using either diethylstilbestrol (DES) or phenylpropanolamine (Propagest Rx in the U.S.). There are more side effects associated with the use of DES but it can be given less frequently, with once a week dosing often being sufficient after the initial treatment period. Phenylpropanolamine has to be given two to three times a day to work well for most dogs. Your vet probably knows the dosages for these medications but I can send them if necessary. It is not unusual for the incontinence to subside after a month or two of treatment so it is worth stopping the medications occasionally to see if they are still necessary to give. As you continue to taper off the prednisone dose there should be improvement in the incontinence behavior since there will be less urine production, so that should help a lot, too. Mike Richards, DVM 10/22/99

Accelerated heart rate in Pit Bull

Q: Dr Mike, The mother of the pitbull with cushings has been breathing more rapidly during the past month or so. And she has been showing signs of being down, especially today. I called our local veterianarian and he got her in this evening. He said her heart rate was 170, so he wanted to do some x-rays to see if she had an enlarged heart. He said from the x-rays that the right side of the heart did appear enlarged and at first was going to put her on Lasix as the lungs looked hazed, but he said the lungs sounded clear when he listened to them. So he said he was going to change and prescribed Lanoxin for her instead. He put her on the low dose of 0.125 mg and said to bring her back in two weeks to see if the heart rate changed any. He said the Lanoxin would slow the rate, plus make it pump better. He also said he would refer to K-State for ekgs if he needed to in the next 2 weeks after her recheck. I, myself had not noticed coughing, but my son said he had noticed it, but didn't think anything about it. Would appreciate your opinion also. Also these two pitbulls have a hx of mass cell disease, the mother moreso than the daughter (with the cushings). Please enlighten us further. And he also told me that Topeka now has an emergency center as of around first part of September. So with all these problems going on, to say the least I was delighted to here this. Ruth (bet you can't tell me dearly love animals, can you?) A: Ruth- A heart rate of 170 is high for any breed of dog but is particularly high for a medium to large sized breed. So I do think you have reason to be concerned and should be working to get to the bottom of this problem. I find, for me, that X-rays are a lot more sensitive way of discovering if there is fluid in the lungs, so I trust the X-ray findings more than my ability to hear fluid sounds. But I do not consider myself to be a good "auscultator", so I can't say that is true for everyone. Ever since cardiac ultrasound has become available I have a hard time working up heart disease cases and thinking I am doing a good job of it, without an ultrasound exam. I practiced for some time before this became a readily available option in my area, so I have treated a lot of heart disease cases without the benefits of ultrasound. But I do think it is the best available test for most of the causes of heart disease. Consequently, if you are close enough to make a trip to K-State to see a cardiologist and have this evaluation done, I'd ask your vet for a referral. If it isn't easy for you to do this, the flip side of the picture is that for most cases of heart disease it is possible to do reasonably good management through the use of medications and adjusting the type and dosage of medication based on clinical responses. Mast cell tumors can cause lots of problems with heart rhythm and blood pressure by producing excessive quantities of histamine in the body. This is something that has to be considered if she has a history of mast cell tumors. It can be pretty hard to find mast cell tumors when they are present but checking for enlargement of the spleen and watching for other signs of histamine release such as itchiness, vomiting, blood in the stool, difficulty breathing and even coughing is important. Unfortunately some of these signs overlap those seen with heart problems unrelated to mast cell tumors. Good luck with all of this. Mike Richards, DVM 9/24/99

Mast cell tumor and urinary incontinence - Dobie

Q: Dear Dr. Mike, I am a subscriber from Costa Rica . You have always been very helpful. Veterinary care is quite basic here so I need all the help I can get. Question number one: the vet found a teeny mast cell tumor on my girl's neck, which was surgically removed and eventually rated/ranked as the most benign. They presecribed predinosone for five days prior to the surgery, but nothing postoperative. Based on what I've been reading lately I wonder whether she should have had the predisone after the surgery. (I thought it was for swelling; I didn't know it was a "treatment.") What do you think? And second question, I corresponded with you about a year ago about my then two year old Natasha's problem with urinary leakage. (She is spayed.) I gave her dexatrim for about eight months, and it sort of worked. More recently, my new vet has prescribed DES. She took it for five days then takes it once a week. She took her weekly dose day before yesterday, and today had an incident where she sat down, then stood up and there was a tiny puddle on the floor where her urine had been squeezed out by sitting on the floor! She had one seizure and passed a bit of blood while urinating about 15 months ago, and it was right around then when she started having this leakage. Also right around then she began having occasional tummy problems: she would eat some grass and vomit. We were never able to figure out if she just liked the taste of grass, but it made her vomit, or if she ate the grass because she felt bad. For the first time in quite a while, she ate some grass and vomited this morning, followed 20 minutes later by the leakage. And she doesn't feel to well now. Could she have a stone of some sort, and would the stone relate to a more serious problem, or should I just not worry about this. Thanks for your help. You truly are wonderful. Wendy A: Wendy- I think it is worthwhile to give prednisone for a while after removing a mast cell tumor, although this may not be necessary when the tumor does not appear to be highly malignant and there is no sign that it has spread. There is some controversy over the effectiveness of prednisone for preventing malignancy but it isn't highly risky so we still use it. We have been using it for 2 to 3 months in our most recent cases. When phenylpropanolamine doesn't work well and we really think that the problem is incontinence we use diethylstilbestrol (DES), too. Usually one or the other of these medications will help. Bladder stones do sometimes cause incontinence, although there are usually other signs, like frequent urination or blood in the urine. Neurologic deficits can develop with age which lead to incontinence. In these cases DES and phenylpropanolamine do not usually help much. Give the DES some time and then decide if it seems necessary to look for other problems. Your vet will be able to help decide when and if this is necessary. Also, consider disorders in which there is increased drinking and urinating, such as hyperadrenocorticism or kidney damage. If Natasha has any sign of these problems consider a lab work up to rule them out. I don't know what to say about the correlation with grass eating. I don't associate it with incontinence. It is always hard to figure out if dogs are eating grass because they want to vomit or are vomiting because they ate grass. Mast cell tumors can cause gastric ulcers. You might want to discuss that possibility with your vet and see if he or she thinks that cimetidine (Tagamet Rx) might help. Good luck with all of this. Mike Richards, DVM

Mast cell tumor

Q: Dear Dr. Mike, I am so relieved to find a reliable source of information on the topic of mast cell tumors in vet. medicine. We have 2 Golden Retrievers--one 5 year old and a one year old puppy. Our oldest, Marley, has recently been diagnosed with a mast cell tumor located on his right hind leg on the outermost toe. It was very swollen for about 8 weeks, the vet had given him Septra DS to see if the cyst would shrink. I am a pharmacist and my opinion is that the chosen drug is not appropriate for anaerobic bacteria normally found in a cyst, nor is it a good choice for skin infections in general. I gave her the benefit of the doubt-she's the vet! The swelling did not go down and when I asked her if she had done a culture she said no. The next visit brought us to the decision of draining the cyst-she couldn't decide what to do at first, but told me to leave Marley there for an hour and she would put him under and drain it. I returned an hour and one half later to find that she had amputated his toe without telling me ahead of time. I took him home and kept him bandaged for a week. We placed repeated calls to her office to no avail as she has not called us back for two weeks. We need to take some action on Marley's behalf and I need to know what our next step should be. I have been giving him vitamin E and I'm considering herbal options. When I asked her about vitamin and nutritional therapy, she mentioned that she had a call in to an oncologist friend and that she would get back to me. Nothing yet. If you have any opinions or suggestions about his case, please contact me. I so appreciate your time! Thank you very much! Kelly C. A: Kelly- I am never sure why there are variations in the way that veterinarians and physicians use antibiotics but I suspect that part of the variation is price sensitivity on the veterinary side. In any case, the sulfa/trimethoprim antibiotic combinations are very commonly used for skin infections in dogs (less so in cats) and are listed in veterinary texts as being among the most efficacious for this use. Most cystic lesions in pets are probably not due to bacterial infection but there are pretty common aerobic and anaerobic infections among the domestic species (goats are commonly affected with "cysts" that are actually walled off abscesses, for instance). I have read an article, unfortunately not one I can easily reference, that had a short tirade against the use of the word cyst to describe any lesion on the foot of a dog. The author claimed that cysts occur so infrequently on dog's feet that the use of the word made it more likely that veterinarians would forget that about 80% of the lesions that look like cysts on dog's feet are actually cancer and that a big chunk (19%) of the remaining ones are pyogranulometous lesions, not cysts. Unfortunately, clients understand the word cyst better and if the vet is hoping that the dog is beating the odds and doesn't have a form of cancer the tendency is to go ahead and say "cyst". As it worked out, Marly didn't beat the odds, which leaves you wondering what to do now. It is very very hard to get all of a mast cell tumor. Amputation of the digit is the best course of action. I don't know why you weren't informed that was what your vet intended to do, but at least it was the right thing to do. Since you are pretty sure that this was a mast cell tumor I am assuming that a pathologist examined the tissue removed. If so, it would be a good idea to get the report and see if the pathologist graded the tumor. There are several schemes for doing this so you may have to consult with your vet about the meaning of any term used to grade the tumor. Once that is known, it is possible to make a plan for the next step. In a tumor graded above the minimal level of malignant appearance (Grade II, Intermediate, ?)oncologists like to suggest aspiration of a regional lymph node (or removal and histopath), abdominal X-rays, general blood work and examination of a buffy coat smear. If all of these things show no tumor spread, then consider aspiration or biopsy of spleen and liver and then finally bone marrow aspiration and cytology -- assuming all steps up to that point are negative. Then if there appears to be no spread of the cancer, radiation therapy around the excision site. If the cancer has spread it is debatable whether anything will help a whole lot but prednisone or H2 blockers like cimetidine may be helpful and some vets still recommend radiation therapy. I am not aware of any recommendations in the veterinary literature concerning vitamin or herbal therapy for mast cell tumors (there were none in the literature that turned up in a database search on the Veterinary Information Network). Mike Richards, DVM

Mast cell tumor surgery

Q: Dear Dr. Mike- I was so grateful to find your web page! My 6 year old pug had a suspected mast cell tumor removed yesterday from above her right shoulder in the ruff area. 10 days to wait until biopsy results are known. The vet says depending on the tumor's stage, treatment would be nothing or radiation. She said nothing about prednisone or antihistimine(as I read on aol's pet care boards) follow-up treatment. Would you be willing and able to help me find some references on Dr. Rodney Page of North Carolina State research and/or others work on prednisone treatment? I think I need "chapter and verse" references to show my vet if my vet is unfamiliar with this treatment. I want to be able to convince the vet this is the right follow-up to give my dog,if it is,. She said her dog had a stage one mast cell tumor and she excised it and that was it. I know vets are busy and cannot always keep up on all the research and knowledge that is coming out. Perhaps I can give my dog her best chance of health and other's dogs, too, if I can find and share this information. I live in New Hampshire. My dog weighs 19.5 lbs and has generally good health. She was rescued by me about 1 and a half years ago. I am at least her 3rd owner. She is such a great dog and I want to give her every chance. Thanks to you and your caring enough about pets and their owners and the bond they share to start this web page. Sincerely, I. A: I may not be able to supply information on journal references from Dr. Page as I can only find references relating to other types of tumors from him, in journals. I have the proceedings from a meeting at which he was the speaker (Richmond Academy of Veterinary Medicine, November 1996) that refer to the beneficial effects of prednisone. According to Dr. Page, prednisone is the only chemotherapeutic agent with proven efficacy against mast cell tumors other than l-asparaginase. Unfortunately, like many things relating to cancers, this information appears to be somewhat controversial. Dr. Karri Meleo, also an oncologist, feels that the prednisone treatment is only likely to benefit about 20% of dogs and that radiation therapy is a better choice post-surgically, based on her postings on the Veterinary Information Network. Cimetidine (Tagamet Rx) is usually used to try to alleviate the irritating effects of mast cell tumors on the gastrointestinal tract -- thus it is not being used as a chemotherapeutic agent but as a means to increase the quality of life in dogs with this tumor. Surgical excision is still the mainstay of treatment for mast cell tumors. Surgery must be done wide and deep (it is best to be at least 1" away from any visible tumor edges in ALL directions). The location of the tumor may make it difficult to get that deep below a tumor but an effort should be made even if it is difficult. Once surgery has been done, the best option is probably radiation therapy, if that is available. If it is not, using prednisone and cimetidine should be considered, since a 20% response rate is still better than none. This response rate is supported by a study by McCaw et. al, in the Nov/Dec 1994 Journal of Veterinary Internal Medicine. Dr. Page does seem to believe that prednisone works somewhat better than this, based on his presentation. If the tumor is well differentiated (Stage 1) then surgical excision is much more likely to be curative than if it is moderately differentiated (stage 2) or undifferentiated (stage 3). If this tumor is reported as stage 2 or 3 it is important to do a more complete staging procedure to see whether or not there has been spread of the tumor. Tests might include X-rays of the abdomen and lungs, fine needle aspirate of the regional lymph nodes (or removal and biopsy), fine needle or other biopsy of the spleen and/or liver, general blood chemistry exam and a buffy coat smear of the peripheral blood and bone marrow to search for signs the tumor has metastasized. If may be helpful to consider referral to a veterinary oncologist if that is possible since they are familiar with this testing procedure. I wish oncology were not so controversial. The "newest and best" information seems to change almost weekly! It makes it confusing to general practitioners but there are oncology specialists to sort it all out. Mike Richards, DVM

Mast Cell Tumors

Q: Dear Dr. Mike: I have 2 pugs (adorable, sweet, my best friends/babies). CoCo, age 5, had a mast cell tumor removed from her chest in July, and 2 weeks ago had a reoccurence removed from the same spot. Path. report said it appeared that surgery had gotten it all, but recommended frequent blood tests and chest Xrays to monitor this. Can you please tell me what the likelihood is of this type of tumor metastasizing & being fatal? A: I can't answer all of your questions from home. I have some recent information on mast cell tumors at the office I will check on, though. What I do know is that mast cell tumors are extraordinarily difficult to remove surgically. In fact, I was at a seminar on cancer in which the speaker said that any surgical removal of a mast cell tumor should be viewed as a biopsy -- not as a treatment. It is necessary to remove at least 3cm (about 1.25 inches) in EVERY direction around one of these tumors to even begin to feel that surgery might remove it all. Most vets won't cut out the tissue 3cm deep to the tumor because that often means that the bone underlying the tumor must be removed and few general practitioners want to do that. Prednisone is considered to be chemotherapeutic in these tumors and the use of prednisone to help control spread of the tumors is commonly recommended. As chemotherapeutic agents go, it is relatively non-toxic. Cimetidine (Tagamet Rx) is often used to protect the stomach from the effect of histamine released from mast cell tumors and may have a more general benefit as well. It is also very non-toxic. I think that radiation therapy has shown some benefit in treating this condition, as well. If your dog is not on prednisone therapy, please discuss this with your vet. Mike Richards, DVM

Mast Cell Tumor Therapy

Q: Dear Dr. Mike, I am very grateful for your prompt reply. I will call my vet tomorrow re the Prednisone therapy for CoCo. The prognosis is disheartening but pretty much what I've read, as well. I am relieved at your reply re Helen K. & Pug Encephalitis. The breeder & I are good friends & he immediately stopped breeding that line when Sunny (my first pug) died. You do a great service to pet owners (or those of us owned by pets!) & I wish you every good fortune. Many years ago I lived in Richmond & spent some lovely weekends on the Rappahanock River, & in Weems & Vienna (before it grew). Again, thanks and kindest regards, A: I found the information on mast cell tumors from the seminar I attended recently. The speaker was Dr. Rodney Page from the North Carolina State University College of Veterinary Medicine. According to the statistics provided by Dr. Page, approximately 50% of mast cell tumors are curable with aggressive surgical removal. Mast cell tumors spread easier in the superficial skin so it is most important to get a wide surgical margin around the edges of the tumor but it is still important to get as deep as possible, as well. It is probably a good idea in any dog affected by mast cell tumors to use prednisone at chemotherapeutic doses for about 6 months post surgery. If there is no evidence of further tumor growth at that time, gradual discontinuation of prednisone is OK. If the tumor appears to be very aggressive based on the pathologist's evaluation (moderately to poorly differentiated), then it may be a good idea to consider radiation therapy, too, if that is an option in your area. The combination of surgery, radiation therapy and chemotherapy seems to give the best chance of long term control according to Dr. Page. Again -- good luck with this. Mike Richards, DVM


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...