Mast Cell Tumors in Dogs: some advances in conventional care
Dr. Demian Dressler is internationally recognized as “the dog cancer vet” because of his innovations in the field of dog cancer management, and the popularity of his blog here at Dog Cancer Blog. The owner of South Shore Veterinary Care, a full-service veterinary hospital in Maui, Hawaii, Dr. Dressler studied Animal Physiology and received a Bachelor of Science degree from the University of California at Davis before earning his Doctorate in Veterinary Medicine from Cornell University. After practicing at Killewald Animal Hospital in Amherst, New York, he returned to his home state, Hawaii, to practice at the East Honolulu Pet Hospital before heading home to Maui to open his own hospital. Dr. Dressler consults both dog lovers and veterinary professionals, and is sought after as a speaker on topics ranging from the links between lifestyle choices and disease, nutrition and cancer, and animal ethics. His television appearances include “Ask the Vet” segments on local news programs. He is the author of The Dog Cancer Survival Guide: Full Spectrum Treatments to Optimize Your Dog’s Life Quality and Longevity. He is a member of the American Veterinary Medical Association, the Hawaii Veterinary Medical Association, the American Association of Avian Veterinarians, the National Animal Supplement Council and CORE (Comparative Orthopedic Research Evaluation). He is also an advisory board member for Pacific Primate Sanctuary.
Updated: May 6th, 2019
Hi! I have been getting feedback about mast cell tumors and I would like to get some info out there. I will focus on some conventional medicine advances for the time being that should be thoroughly checked into by dog lovers interested in mast cell tumors. These are not general cancer recommendations, rather just a window to full spectrum care, which is a phrase I coined to describe evidence-based selection of cancer fighting weapons from any source. I will focus on Western (allopathic) viewpoints today.
First, the traditional treatment is surgery…get ’em out. I wrote about pre-treatment with Benadryl before surgery, in a previous post, so remind your vet. Have any mass aspirated (needle biopsy) before surgery to diagnose most mast cell tumors so your vet surgeon has a general diagnosis before surgery.
Chemo consists of drugs like prednisolone, vinblastine, and others traditionally. Chemo in dogs is tolerated better than in humans as lower doses are used for cancer. The word “chemo” has a bad ring to it, but this is a prejudice developed from human medicine. Dogs generally handle it better, on the average, although everyone is different.
Note: if you have a Collie or related breed, make sure your vet tests for a MDR-1 gene mutation common in these herding dogs. This genetic issue may increase chances of side effects not only from vinblastine (above), but also vincristine and doxorubicin. Doses of these drugs shoud be lowered significantly if your dog is positive on this test. For more information, see the post on 8/30/08.
Predisolone or prednisone (“pred”, ) are cheap, common, side effects are most often not too bad, and they are tablets so you can change the dose easily depending on your dog’s responses. Vinblastine is a stronger chemo vinca alkaloid chemo agent, more potent than pred, which requires the dog to be in the hospital for injections. Some oncologists like cyclophosphamide and L-asparaginase (you’ll get different opinions and preferences from different oncologists). These are all used for mast cell tumors.
Some stats for Grade 3 mast cell tumors treated with surgery, pred, and vinblastine: At 1 year after surgery, 57% of dogs were still alive, and at 2 years 45% were still alive. Average remission times are about 10 weeks to 5 months with surgery, prednisolone, and vinblastine. Remember, every dog is different, however.
Radiation is used for mast cell tumors that are difficult to remove completely, or any grade 3. This can be high voltage radiation, or brachytherapy, which involves the use of radioactive implants within the tumor site. Yes, a little weird, involved, and costly, but long remissions in the literature.
For more helpful information and tools on Mast Cell Tumors, get a copy of the Dog Cancer Survival Guide
Many are not into invasive care, so take a look below:
One that should be considered for a less intensive protocol is Lomustine or CCNU. This drug has gotten a lot of attention in the last couple of years for good reason. It is a pill,and can be given every 3 weeks. Pretty easy and non-invasive, unlike most chemo protocols, and is a single agent so it is simple. About 40% of dogs with mast cell tumors respond to CCNU all by itself, which is pretty darn good.
Cimetidine should be used in dogs with mast cell tumors, especially those with decreases in appetite or vomiting. This is an antacid which kills two birds with one stone. Mast cell tumors cause excessive acid production in the stomach when they get bad, which cimetidine counters. Additionally, cimetidine has some good anticancer effects that have nothing to do with acid stomach. Finally, it is cheap and easy to get.
Ask your vet about intralesional triamcinolone. They may have not used it before, so do not be surprised, but they can access the info easily (1 mg per cm q 2-3 weeks SQ). It is an simple injection of a form of cortisone that most vets will have sitting on their shelves. It is not very expensive, and very common. Every 2-3 weeks, your vet can inject the mast cell tumor, or infuse the area where the mast cell tumor was removed, with a small dose of this drug. The direct contact of the triamcinolone with any mast cells left in the body will blast them pretty good.
A new drug called SU 111654 (great name eh?) is being worked on at Michegan State University. Looks promising. There is also a technique out there consisting of injecting the mast cell tumor sites with deionized water. Cheap as dirt, but mixed reviews.
This post is just a piece of full spectrum cancer care for mast cell tumors folks. There is a lot more, but I’ll let you sink your teeth into this…
Best to all,
Dr Dressler
Dr. Demian Dressler is internationally recognized as “the dog cancer vet” because of his innovations in the field of dog cancer management, and the popularity of his blog here at Dog Cancer Blog. The owner of South Shore Veterinary Care, a full-service veterinary hospital in Maui, Hawaii, Dr. Dressler studied Animal Physiology and received a Bachelor of Science degree from the University of California at Davis before earning his Doctorate in Veterinary Medicine from Cornell University. After practicing at Killewald Animal Hospital in Amherst, New York, he returned to his home state, Hawaii, to practice at the East Honolulu Pet Hospital before heading home to Maui to open his own hospital. Dr. Dressler consults both dog lovers and veterinary professionals, and is sought after as a speaker on topics ranging from the links between lifestyle choices and disease, nutrition and cancer, and animal ethics. His television appearances include “Ask the Vet” segments on local news programs. He is the author of The Dog Cancer Survival Guide: Full Spectrum Treatments to Optimize Your Dog’s Life Quality and Longevity. He is a member of the American Veterinary Medical Association, the Hawaii Veterinary Medical Association, the American Association of Avian Veterinarians, the National Animal Supplement Council and CORE (Comparative Orthopedic Research Evaluation). He is also an advisory board member for Pacific Primate Sanctuary.
I have written to you before about our 2yr old lab Farley and hope you can help once again. He has DJD in elbows and hocks as a result of OCD. He received stem cell therapy in March of last year. He had 2 Grade 1 mast cell tumors (2cm clean margins on abdominal tumor and 2mm clean margins on tail that resulted in amputation of his entire tail) removed on September 13 and only days after I discovered 2 very tiny lumps on one of his ears that come and go. He had a 3rd Grade 2 tumor removed from the inguinal area on January 27th and a biopsy of one of the lumps on his ears revealed it too is a mast cell tumor (the other lump on his ear had reappeared, but again vanished). His oncologist is recommending chemo (Vinblastin) for a number of reasons that include the location of this 3rd tumor. A rep from the company that sells the in-office stem cell treatment kit agreed that if he had an active tumor at the time of stem cell therapy, that the therapy may have aided tumor proliferation. In retrospect, I am quite certain that the tumor on his tail was active at that time, although we were not aware of it. The first two tumors had a mitotic index of 0 and the oncologist said that the 3rd tumor is quite inactive as well (I don’t know the mitotic index and haven’t seen the histology report yet). My concern is that the stem cell therapy in addition to the relatively inactive tumors may render the Vinblastin treatments pointless or perhaps invite another more serious onslaught of tumors. Two days following this most recent surgery, about a dozen more lumps erupted suddenly, all in the inguinal area. Most have diminished or vanished altogether. There is very little information available, and my follow up question to the stem cell treatment kit company has gone unanswered. Would you hazard a guess as to whether these tumors will continue to pop up in rapid succession if the stem cell therapy is involved? I have read that stem cells are more resistant to chemo. In light of that and since chemo is most effective on more active tumors and Farley’s are relatively inactive, is chemo futile. I feel sick to think that I enthusiastically agreed to a treatment I believed would help my boy, and that decision has now placed him in a life-threatening position. I thoroughly researched stem cell therapy prior to treatment and felt confident that he would be safe. Readers considering stem cell therapy for their beloved companions should be made aware of the risks in terms of undetected cancer. Any advice would be greatly appreciated. Our next visit with Farley’s oncologist is on Monday. In spite of all of his troubles, he remains a happy-go-lucky loveable lab, albeit an obese one that drags me to the door of our vet and to the door of the teaching hospital he is being treated at (OVC, Guelph, Ontario) eager to meet all of the staff and other clients.
Many thanks,
Mary McDonald
We just found out today that our dog Aubie has a growth assumed to be a tumor just above his left hind leg. I have been researching cancer in dogs since because the vet aspirated the area and said she is pretty sure it is cancerous but cannot tell us how bad it is until the tests return in a few days. My big concern is that the original sign of this started in November while we were away on vacation but by the time we got home the area had gone down and his demeanor was normal. Off an on since the area would swell but his demeanor and appetite never really changed other than him favoring his leg from time to time. Aubie broke this leg severely when he was six months old (he is now almost 10 years old) so we assumed (bad idea I know) that it was old age catching up to him. However, in less than 24hrs he stopped eating and refused to get up even to go outside. Does that mean that we should expect the prognosis to be bad since its been almost 3 months since the first symptoms occured??? I just want something to be optimitic about if possible. Thanks for any advice you can give us.
Angela
Hi. I have an 8 yr old Rottie who is the sweetest most affectionate dog I have ever had- I love him to pieces. He has always been a happy, healthy boy. Within the last 2-3 wks, my husband and I noticed a small (maybe almond sized) lump under his skin around his neck region. Over the last week, we found several more lumps, including a couple very small ones on the top of his head. I took him to the vet immediately, where they tried to do a needle aspiration on the several lumps we knew were there. When I picked my Rottie up and met w/ the vet, he reported that he was unable to get anything out of the lumps because they were too hard (all that would come out was blood). He said at that point that he didn’t necessarily think they were cancerous as they didn’t appear to be agressive types of tumors (but this was just his opinion as no pathology could be performed). He recommended that I keep an eye on the lumps and monitor growth, and if I felt necessary and/or if they were growing quickly, we would go ahead and remove. That was just a few days ago, and I have already found several more lumps, some bigger than others. Not only in the head/neck region now, but also on his left front leg and on his left rear leg (way high up, almost at the top of his “haunch” if that makes sense). I called my vet today to report this and to see what we should do (I’m awaiting a call back). My gut tells me this isn’t good (that lumps keeping popping up, and so rapidly). Is it possible these are non-cancerous? I don’t understand why all of the sudden they seem to be popping up everywhere… it almost seems like removing them would be futile as they just keep coming. Of course I want to do WHATEVER is needed and whatever keeps him as healthy as possible and in little/no pain. I guess I’m just looking for some advice as to what the possibilities could be, and some encouragement that we should try and get all of these lumps out asap. Thanks very much for any insight. I’m also going to look into some holistic approaches in terms of diet/supplement… maybe that will stop the spread of more lumps??
Dear Janel,
the important thing here is to get a diagnosis. Perhaps the way to go would be an impression smear of an abraded lump surface, or other testing (removal, biopsy, etc). Please insist on getting some answers!!
Best
Dr D
Danny is 11 years old and it started the back of his upper legs but there the size of soft balls. He has had them for years now and the one that’s humongous is where he was fixed. Also under his joints ( legs) these are the size of baseballs. + it appears 2 more are growing. All are around major muscle areas. BUT whats weird is he hasn’t lost his appetite + he still runs in the yard and likes to still go for walks. If these were cancer you would think it would effect him in many ways. We can’t afford to take him to the vet now. He eats home made dog food along with the other dog we have 4 altogether. Danny is part lab and part beagle but is about 80 lbs. looks like a rottweiler.
He has 7 of these growths now
Dear David,
please get these checked at the vets and get a diagnosis. Here’s some info about cost savings (and there is more in the Guide)
https://www.dogcancerblog.com/blog/the-cost-of-my-dogs-life-part-1/
Yes, dogs will start to act sick as cancer progresses in one way or another. But “acting normally” does not exclude cancer, just like a woman with a cancer in the breast that is malignant acts normally in the beginning (and will take her life, but later).
Please read this post for more info:
https://www.dogcancerblog.com/blog/signs-of-dog-cancer-and-decompensation/
I hope this helps
Dr D
My pitbull had a grade 2 MCT on his hip removed last year, with clear margins. Now one year later, he has a MCT between his 2 toes on his hind leg. My vet would like to amputate both toes. Then start chemo. I only have one more day before the surgery. Is this the way to go?
Three years ago, my beloved dog was diagnosed with a grade 3 mast cell tumor on her muzzle. The tumor had spread to her local lymph nodes, and the doctors did not give us much hope. Nevertheless, we treated aggressively. The tumor couldn’t be removed surgically, because it was too diffuse (a bad sign), but they did remove the lymph node. We treated with radiation on the tumor and lymph node site, and we did a combination chemotherapy of vinblastine and prednisone. I sought the help of a holistic vet, and we put together a special diet, including herbs and supplements. Three years later, she is cancer-free. I know that this isn’t typical, and I feel grateful every single day. I am posting this only because, when I was so devastated and searched for signs of hope, I couldn’t find any. Everything I read seemed to suggest that my dog would not survive. The treatment was hard on her, and it was expensive, but the years since have been priceless.
Danya, I wish you the best. My dog, Ella, was five when she was diagnosed.
Hello Dr Dressler,
My 4 yr old female yellow lab…..that I love more than any pet I;ve ever had has an aggressive form of mast cell cancer. We discovered an aprox. 10mm red wart-like bump on left back leg…muscle area. Initial biopsy came back grade 3. Our vet removed tumor w 3cm border and sent it off for biopsy. It came back as high grade 2 with clean margins. She has been taking benadryl, prednisone and tagamet from the initial biopsy along with antibiotic. We decided to treat her with prednisone and vinblastin, today was her first treatment. When I took her in today, our vet had just gotten the tumor profile. These are the results; MI=82; Ki-67=high; c-kit= I-80%, II-20%; c-kit mutation status= Exon 11. I know this is very bad. The vet checked her nodes with ultrasound before giving the vinblastine. They are normal size. I guess what I would like to know is should we even put her through the chemo treatments? My vet says vinblastine is tolerated pretty well, but I still do not want what is left of her too short life to be hell for her. What can I do to make it better for her? My heart is broken and I don’t want her to suffer.
Thank-you for your kindness,
Dayna
Dear Dayna
I am sorry to hear about this. This is a treatment plan analysis question. Young dog and so I would tend to be more agressive personally as your girl could conceivably have a long life (not yet near her life expectancy). But it depends on what your priorities are. You need to get data on life extension and odds of risks, and what are these risks in your dog, and then decide whether these gains versus costs fit with your principles and needs for your dog.
You should read the treatment plan analysis section of the Guide definitely.
Here is a blog you may find helpful:
https://www.dogcancerblog.com/blog/what-is-treatment-plan-analysis/
I would be also thinking about diet and supplements too!
Best
Dr D
She is 5 years old and is a bulldog
Dear dr D,
My dear Australian Shepherd, Jaeda, has been diagnosed with MTC in liver and spleen. The first one is 2,5 cm and the the other one is 3-4 cm. Only a week ago they were 0.5 cm and 2 cm, so it is growing very fast. My vet told me about Masivet but since it is very rare that MTC starts in liver and spleen, he has no record of results or any prognosis. I really don’t want to loose my dear dog, but i am very insecure about what to do. Considering the agressive way it grows, the fact that the tumor is already bleeding, I think there is nothing more that i can do. Please can you think with me, since you have the experience. What should i do?
Warmest regards,
Hylke Walters (the Netherlands)
Dr. D
My 16 year old pug Vic has a mast cell tumor on her right hind leg. She’s had 2 mct’s removed before. One on her neck at age 5 and one on the same leg at age 10. Considering her age we don’t want to do surgery and chemo again. Her hearing is gone and her sight failing but otherwise she’s healthy. What noninvasive treatment or drug might be useful?
We have her on benefryl twice a day.
Thanks
Mike
Our 8/9 year old lurcher/german sheppard cross had a grade 2 mass cell tumour found last November and has been on Masivet 150mg, 2 pills a day, and the tumour has gone ! she has had no side effects in this period, it was the drug or to lose her lag, we took the chance and up to now it’s been very ( fingers crossed ) successful, the cost is £300 a month.
Good luck
Dear Bazzer,
this is good news! I was involved in some of the early use of this drug before it was approved here in the US and have had good results. Thanks for the input.
Don’t forget diet, supplements, immune support, and life quality enhancement of course!! More in the Guide if you have interest in these options.
Best
Dr D
With a sled dog kennel of Alaskan Huskies I have had several cases of cancer and any information I can receive is valuable. Currently my retired leader is receiving chemo for a MCT grade III. He’s in his third week of vinblastine, pred, and Benedryl. Amazing how the tumors (2) shrank.
Thank you for all the information.
Gayle,
Glad you found the posts helpful and informative. I recently wrote a whole series on MCT. If you are looking for more info, start here:
https://www.dogcancerblog.com/blog/the-oncologists-thoughts-on-mast-cell-tumors/
And here’s one on chemo:
https://www.dogcancerblog.com/blog/mact-cell-tumor-treatment-chemotherapy/
All my best, Dr Sue