The Oncologist’s thoughts on mast cell tumors
Sue Ettinger, DVM. Dip. ACVIM (Oncology). Dr. Sue is a boarded veterinary medical cancer specialist. As a Diplomate of the American College of Veterinary Internal Medicine (Oncology), she is one of approximately 400 board-certified veterinary specialists in medical oncology in North America. She is a book author, radio co-host, and an advocate of early cancer detection and raising cancer awareness. Along with Dr. Demian Dressler, Dr. Sue is the co-author of The Dog Cancer Survival Guide: Full Spectrum Treatments to Optimize Your Dog’s Life Quality and Longevity.
Updated: November 22nd, 2018
If ever there was a tumor that fits the saying: “one size does NOT fit all”, it is mast cell tumors (MCT). These tumors are common, particularly skin tumors, in dogs. You may know a dog that had a mast cell tumor removed with surgery and went on to live many happy years to never hear from the MCT again. On the other end of the spectrum, you may know a dog with an aggressive MCT that recurred and/or metastasized quickly and lived just a few months.
What gives? Why is there so much variation in outcome? If your dog has a MCT, will it be a “good” MCT or a “bad” MCT? Can that be predicted? Why is there a new grading system? Do the new c-kit inhibitors (Palladia and Kinavet) work? In my next series of blogs, I hope to answer many questions about the complicated mast cell tumor.
First, let’s understand what MCT are. Normal mast cells are a type of immune system cell and play an important role in inflammation. While other immune system cells tend to circulate throughout the body, mast cells don’t – once they mature, they take up residence in specific tissues. While they can be found anywhere, many live in tissues that mark the boundary between the outside and internal environments; for example, the skin, the mouth, the digestive tract, the nasal passages, and the lungs.
Mast cells hold structures inside their cell walls called granules, which are like little sacks. The granules are filled with substances, or cytokines, including heparin and histamine, which help the immune system respond to problems. Heparin is a blood thinner which helps defend the body against foreign invaders, and histamine is a chemical that triggers inflammation. Normal mast cells release these substances when prompted by the immune system. In addition to their role in inflammation, mast cells are involved in allergies, anaphylaxis (systemic inflammation), the healing of wounds, and defense against outside pathogens.
In this seminar, Dr. Dressler addresses a number of important topics on Mast Cell Tumors, so be sure to get your copy for more information!
Mast cell tumors are cancerous accumulations of mast cells with a malignant potential. MCT is very rarely found in humans, but it is the most common malignant skin tumor in dogs, accounting for 15-20% of all skin tumors. Mast cell tumors first occur in the skin and the subcutaneous tissues beneath the skin. It’s very rare to find MCT in internal organs without a primary skin tumor, but skin tumors can spread to the regional lymph nodes, the spleen, the liver, other places deep in the abdomen, and to the bone marrow.
What causes MCT? Like most tumors, the exact cause is not known. About one-third of dogs have a genetic mutation in a protein called the c-kit oncogene. Unlike skin cancer in humans, which is often associated with sun exposure, studies have found no link between sun exposure and MCT in dogs. But chronic inflammation of the skin may predispose dogs to develop MCT, as can the repeated application of skin irritants.
We also tend to see it more commonly in the following breeds: Boxers, Boston Terriers, Labradors, Golden Retrievers, Pugs, and Staffordshire Bull Terriers. Boxers tend to develop low and intermediate grade tumors.
MCT are one of the most common tumors I see in my oncology practice at the Animal Specialty Center. When should you see an oncologist for MCT? We will pick up there at my next post. In the meantime, remember there is a lot more information about MCT in the Guide.
Get the book to read more on Mast Cell Tumors from an Oncologists Perspective!
Sue Ettinger, DVM. Dip. ACVIM (Oncology). Dr. Sue is a boarded veterinary medical cancer specialist. As a Diplomate of the American College of Veterinary Internal Medicine (Oncology), she is one of approximately 400 board-certified veterinary specialists in medical oncology in North America. She is a book author, radio co-host, and an advocate of early cancer detection and raising cancer awareness. Along with Dr. Demian Dressler, Dr. Sue is the co-author of The Dog Cancer Survival Guide: Full Spectrum Treatments to Optimize Your Dog’s Life Quality and Longevity.
My golden retriever has recurring Mast cell tumors. She has 4 or 5 very small tumors right now…..actually hard to find.
They don’t bother her for the most part, but if she starts scratching and snags one of the bumps it gets really itchy and I spray hydrocortisone spray on it directly. It seems to soothe and eventually they are not so irritated and the redness goes away. Would you recommend using this all the time ? She takes a lot of supplements (apocaps) and other pills so I don’t like to overdose her on taking more pills. Also, has there ever been a procedure done to try to freeze the Mast cell and remove ? She had had several surgeries and between the anesthesia and the healing time it’s a lot to put her through.
Hello Sandy,
Thanks for writing. As we’re not veterinarians here in customer support, we can’t offer you medical advice. You do have to be cautious when making any changes to your dog’s current treatment plan, this is why we always recommend consulting with your vet to get their approval. They will be able to let you know what you can do to help with the scratching, and what you can safely use on the bumps for your specific dog 🙂
My dog (about an 11 year old lab/Australian mix) has had a stage 3 mast cell tumor removed from her nipple area. Not sure how to proceed.
My 10 year old frenchie was diagnosed with bone cancer in her nasal passage and given 4-6 months, it’s been well over a year, either having her blessed or the herb Yunnan Bayiou has worked or could it be mid diagnosed? Lately her appetite has increased dramatically but she’s off balance, have to carry her for stairs and she trips and falls over easily. Confused that she is eating great but off in other ways. Could the cancer be spreading or could it be hearing and vision or senility? I don’t want her to suffer.
Hello Dee, thanks for writing! I’m so pleased to hear your girl has been going strong for so long — that’s wonderful! It sounds like another visit to the veterinarian is in order to find out what is causing her symptoms. Nasal tumors sometimes grow into the skull and impact the brain, so it’s possible that the tumor hasn’t spread, necessarily, but has invaded other areas and is impacting your girl’s balance. But it could be something else, too. There’s really no way to know for certain without a veterinarian examining her. They will be able to at least eliminate as many other causes as possible. And if there is something that might help, they’ll know what it is. Many blessings.
Hi I am Jacquie Zelcer, all the way from Auckland, New Zealand. I am just requesting some advice as I see you are experts in the field of MCT. My 13.5 year old shih tzu dog Charlie, has had x3 MCT – the first 2.5 years ago where he had x4 rounds of vinblastin and helixor. In the past 3 months he has had 1 large MCT removed (vet says doesn’t look like it has gone to liver or spleen) and now a new one has appeared this week (large pink spongy dome under his rib cage). Had a needle biopsy, came back positive MCT and unusually, they commented it was aggressive and intrusive. Options are yet another operation to remove (dog is not coping with operations his quality of life has gone down). Our dilemma is do we remove this MCT or do we let our dog live out his last days tranquilly. He is on meloxicam 0.7mls and neurontin every day for pain (reumatism) do we stop this and give him Prednisone? I would love to hear your opinion if it is not too much trouble. Regards, Jacquie
Hey Margaret,
You should look at Texas A&M Small Animal Hosptial, for your Mast Cell Treatment, I had a dog have 3 MCT removed with ultrasound, X-rays, fine need aspiration, for $1400, and now he needs chemo and that is only $2000. They are also one of the best Oncology departments in the US.
Best of luck
After $6700 worth of tests and 3 days care at a specialty pet hospital, my dog was diagnosed with a Mast Cell tumor internally on the chest wall between where the neck end and chest begins? I find this an odd diagnosis for this type of tumor but certainly something is there causing compression and swelling, as well as difficulty swallowing/breathing. They left no stone unturned to find something to treat, that’s for certain. They started her on Palladia yesterday, Ignoring the significant expense, I am not hearing from anyone but the prescribing Vet that this has the likelihood to do much of anything long term except make her sicker. I feel I’ve been taken advantage of, as the emotions involved at a time like this generally don’t allow rational decision while you are in the middle of it. The Oncologist telling you they’ve been in the field 20 years and your skepticism and reluctance are the result of being ignorant on the subject is manipulative at best. After investing that much cash to find out you aren’t going to be able to “save” them, you are then coerced into attempting to “extend” their life a few months for a $10,000 investment. This is abusive at the very least as it is not only emotionally devastating but financially a disaster for many. We will be paying the credit card off long after Sadie has left us.
Question of very LONG-TERM, low dose corticosteroids for CAD.
My last mixed-breed dog, an Armenian born intact male, lived 18yrs 2 months. He suffered with immunity issues which at a young age 3-4 yrs., were treated w expensive, allergen elimination treatment–you now the drill. At age 11yrs. we lived in So. FL; his allergies were worse & unrelenting. So my Vet (in PA) & I discussed a protocol, I really wanted to give a shot. It was, 1mg Prednisone q.o.d. in Summer & .05 -1mg every 3rd day when allergies diminished or abated in winter months. When he was so so old & too weakened to enjoy barking at the mail-man–by 18 yrs of old age–we decided to euthanize him.
My Vet & I were eager to see what side effects or physiological changed occured w low-dose steroids. We did a thorough Post-Mortem head to paw. The ONLY abnormality we saw was a small 3mm non-malignant mass on his L Adrenal.
I now have an Aussie with severe CAD. We’ve tried Apoquel x 2 yrs. It became totally ineffective. Are considering Atopia next. However, what are your thoughts on the same protocol we used on my Armenian dog?
Both my vet friend & I were shocked that he didn’t demonstrate more pathology than a simple Adrenal mass. Your thoughts please?
P.S.Interestingly, this low-dose steroids did in fact, ameliorate ALL major allergic symptoms, for 7-8 years on steroids. The only side effect easily understood, were those seen with steroids: slight weight gain, polydipsia, polyuria, some oral candida etc. BS wnl no neurogenic symptoms-basically general good health ).
I have a chinese sharpei he have s tumor between his legs near his tummy,it is getting bigger like a gholf ball,and it is hanging is it painful
Hello Dr Ettinger,
I have an 8 year old puggle (pug/beagle cross). She has been in very good health. However, she had her first MCT diagnosed in April this year, on her shoulder which was removed but found to be a Grade 2 MCT requiring further surgery and tissue removal, which was then all clear. At the same time, 2 minor cysts were removed from either side under her rib cage which were nothing more. Then a cyst which she had on her lower hind leg for 18 months, was re-tested and diagnosed an MCT, after removal it was another Grade 2. Her scans shows no spread to internal organs and she was clear in August. Unfortunately a small lump developed on her other hind leg last month, which was quickly diagnosed as MCT and removed successfully, another Grade 2. My question really is with her history in a short few months, is there any treatment which may reduce the likelihood of another MCT? She is a very active, happy dog and has bounced back without issue after each surgery. I am very apprehensive at present about a re-occurance and I want to give her the best chance of avoiding further surgery. Many thanks, Paula.
Dr. Ettinger: My 3.5 lab bitch had developed a small mass just below her rib cage midline on the torso. She had whelped 8 healthy pups 7/21/2017, and the little mass appeared just about two weeks before the pups went to their new homes. She also developed an minor itchy rash (small red bumps, which dried quickly and flaked/itched off) on her belly. At the time I did not connect the two — but the rash was clearly a contact allergy and was most likely caused by the continued exposure to whelping box pads that had been relentlessly bleached between uses. The rash lasted less than two weeks and its clearing coincided with her return to “no puppy” and “no pad” status. She has otherwise been bursting with healthy and and trouble free. Just had the small lump (about the size of a cashew) surgically removed on 10/24/2017 and am waiting for the path report. I have given my self a serious crash course in mast cell tumors, causes, treatment, etc., and my one question while I’m waiting for the path report is the question of breeding her a second time. Would you recommend she not be bred again, regardless of whether or not the tumor is classified a zero or 1 on the scale and has a low mitotic index?
I’m not a Vet, just a nurse who’s had so many dogs over 30 yrs. (including dogs my twin sister & neice, couldn’t care for) Ergo we’ve had many, MANY vet visits. My vet & I are close friends and often discuss K9 disorders (especially immune mediate complexes) and of course other disorders. When I first read your description of “small mass just below her rib cage..” I had chills. I wonder if you’d share what the biopsy showed & the definitive diagnosis of that “mass” showed? I certainly hope it was benign. Thanks Dee