Skip to content
Featuring Demian Dressler, DVM and Sue Ettinger, DVM, Dip. ACVIM (Oncology), authors of The Dog Cancer Survival Guide

Mast Cell Tumors in Dogs: some advances in conventional care

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


Leave a Comment

  1. Meagan on December 22, 2012 at 9:32 am

    My dog has a very bad swollen head and throat I gave her 20 ml of Benadryl its urgent it has swollen that fast in just a few hours I cant afford a vet but she is very important to me could she have cancer or does anyone know something I can do for her

  2. Jessica Finnegan on November 30, 2012 at 6:47 pm

    My female boxer Mickey is 6 yrs old and she has been diagnosed with a mast cell tumor. She’s had it since about April of 2012. It is about the size of a swollen dime. I am obviously hoping it is only a stage 1. She has an appointment to get it removed this Tuesday. I was just checking her for more possible bumps and I found two small bumps. One on her right leg and one under her right leg (armpit area) both very small. Could these possibly be mast cell tumors as well? And does that mean this has possibly spread through her body? She has had no symptoms and has been acting completely normal. I am just so worried for my baby. Any opinions would be helpful.

    • Dr. Demian Dressler on December 26, 2012 at 12:54 pm

      Dear Jessica
      definitely get those checked as well! Once the cytology or pathology report is back you can see whether you will need to take further actions on those masses. I would also read this post so you can start getting familiar with your “cancer toolbox”
      Dr D

  3. Francisca on November 30, 2012 at 1:45 am

    Dear Dr Dressler,

    my 7-year-old brittany spaniel mix was diagnosed with mast cell tumor 3 months ago. This is the third one in 3 years,( 2009-2012).

    The first mast cell tumor (one third inch wide-8 mm, I grade) was removed in the inguinal region in july 2009; the second one (one sixth inch wide- 5 mm, I grade) was removed from her chest in August 2011. The third one, on her chest again, formed mid-August…it’s again a tiny one (5mm x 6mm). It’s not been removed yet because most of the time it’s invisible or it appears as a very pale spot, so surgeons say they can’t see its margins clearly…The problem is the dog started to have gastric issues from july on (Her stomach has always been a bit delicate: she occasionally throws up gastric juices especially in the morning when she gets up) but now it happens more often, let’s say once or even twice a week…Can it be related, maybe because of the histamine release?

    At the moment I’m giving her 100 mg of curcumin twice a day, but I was thinking about introducing a quercetin/bromelain supplement for her…Can you help me finding the right dosage considering she weighs 8 kg…and what would be the dosage if, in the future, after the surgery, as a prevention supplement?

    Thank you very much.
    Francisca & Milly

    • Dr. Demian Dressler on December 26, 2012 at 12:31 pm

      Dear Francisca
      you may want to discuss with your vet getting some imaging dones (especially an abdominal ultrasound) to see if there are internal mast cell tumors that could be creating the stomach upset with histamine excess. That is your first step. There are a variety of ways to help with tummy upset- famotidine, omeprazole, mirtazapine, and others. Antihistamines might help. slippery elm sometimes is useful.
      As to supplementation, you should read the Dog Cancer Survival Guide where all the supplements have been discussed for dogs with cancer.
      Dr D

  4. kaisa hegg on November 7, 2012 at 9:19 am

    Dear Dr.Dressler

    this is a great Blog. My rescue greyhound was diagnosed with nasal cavity mast cell tumor at the age of 2 year and 1 month. The Biopsy was done february 2012. Since then I have been trying to treat her holistic and she has been super fit. full of play and endurance but her tumor in her nose has kept on growing steady. I am now considering the drug Masivet but heard the dog have to have a mutation of protein receptor /c-kit, and my vets do not not want to prescribe me this simply because they never heard of the drug and does not know how to find out if she has this mutation that speed up cell division. Do you know how I can find out how she has this mutation,and even if she does not,can this drug still work ? I am based in the uk

    Guardian of Shasha

  5. Lynda on October 22, 2012 at 1:16 am

    My 13 yr old Lhasa apso Oscar was diagnosed with a mass cell tumor after the vet removed what he thought was an umbilical hernia. He had a follow up op after it was found that there were still malignant cells around the edges of the tumor.
    This was approx 6 mths ago.
    Oscar was like a puppy after this operation but about a month ago he began feeling off color and not eating very well.
    I made a routine appointment for 11th Oct to take him to the vet to have a check up and possibly blood work to see if anything had returned.
    On the days leading up to the appointment Oscar started vomiting small amounts of bile, this wasn’t unusual for him if he didn’t eat. On Wednesday evening 10th Oct Oscar brought back the whole of his dinner and continued to vomit throughout the night. It was clear slimy water. next morning I left him for 4 hours to go to work and when I came home he had died!!!!!
    He had had a blow out of blood and mucus and made his way upstairs and died. The vet diagnosed HGE .
    I am at a loss as to how my Oscar could take ill and die within hours. I am devastated.
    An anyone help me with answers to what could possible have been the problem.

  6. Laura on October 18, 2012 at 9:52 am

    Hello, i’d be so grateful for your input.
    My 11 y/o choc lab has been diagnosed with a low grade 2 MCT on his flank, mitotic index of 1. The vet removed some of it, but the margins were dirty – she now recommends a wide excision with a more experienced vet. she has prescribed Piriton an antihistamine.

    She dosen’t seem that clued up really, she hasn’t heard of apocaps (‘snake oil’ she said 🙁 – I have ordered them anyhow… Ive read your book and have started Dylan on the reccomended diet, I’ve heard good things about tagamet and benadryl treatment…but why has my vet not suggested this? Ive little confidence in her 🙁 I can buy these at the chemist, is it okay to give Dylan human meds? what should the dose be, and for how long should I keep it up?

    I really struggled to afford the first surgery, the second will cost over a £1000, so it isn’t really an option, unless i can think of a way..

    Please, please give me your thoughts and advise me of the dose and duration of the tagamet/benadryl treatment…I feel Im struggling alone here…

    I know you must have a million of these requests but I’d be so grateful for your input.
    Thank you SO much,
    Laura and Dylan

  7. Mike Heller on September 24, 2012 at 4:28 am

    Dr. Dressler
    My 10 yr old vizsla has had a history of fatty masses. However, a week ago, a hard, golfball sized mass sprung out, within a few hours, above her right shoulder. In addition, two more new marble sized masses are also evident. Took her to vet and awaiting results of needle aspirate. Bloodwork is normal. Since I have a feeling the mass will need to be surgically removed is there a great surgeon you can refer me to in northeast Florida ie Daytona to Jacksonville…and could also include Orlando?

    • Dr. Susan Ettinger on September 24, 2012 at 4:24 pm

      Mike, I think I answered your question on my Facebook site. Await the aspirated results, so that can help determine whether cancer and the type. Then you can get to a surgeon or oncologist based on the aspirated results. Depending on the tumor type, you may want to see the oncologist before surgery in case we should be looking for spread before surgery, called staging. Also a good resource for an oncologist is and click on find a Specialst. You can also ask your vet for a referral too. Good luck!
      All my best, Dr Sue

  8. Liz Miller on March 27, 2012 at 6:35 am

    Hello Dr. Dressler,
    My two year old boxer has been diagnosed with grade 2 mast cell cancer. He has had one tumor removed in October 2011 and one removed March 2012. The second tumor biopsy results came back with dirty borders. Both tumors were in the same area of the leg.

    I am interested in having the intrelesional triamcinolone injections for my dog. We live in PA and have a veterinarian who seems willing to do it. The article said every 2 – 3 weeks but mentions nothing about the amount of times it would need to be repeated. Do you know how many times the injection should be given?

    Also is there more specifics on the dosage? My dog has about a two to three inch incision. The location of the cancer is his left back leg at the backward facing knee…the hock area, in the hollow (like the hollow area of a human ankle). Best description I can give of the area. I can send pictures if you give me a place to send them to. I can get more information on the amount of tissue taken if you need it. Due to the sensitive area and the fact he will now have a lot of scar tissue would you recommend he be “put under” for the procedure?

    Also can this be done along with prednisone? He will be starting that once the incision heals.

  9. Would giving a dog worms help with mast cell tumors? on March 14, 2012 at 6:31 am

    […] can u tell if ur dog has worms?If my dog has worms, is there a chance i’ll get it?Mast Cell Tumors in Dogs: some advances in conventional careMast Cell Tumors in Dogs: some advances in conventional care#split {}#single […]

  10. debbie calvert on February 29, 2012 at 4:24 pm

    Hi DR. Dressler, My dog just finished his 4 th melonoma vaccine for malignant melonoma of the mouth, We opted not to have 3/4 of his jaw removed, tumor growth was ablated twice, for comfort and odor control. Our oncoligist now recommends giving cyclopkhosphamide QOD, very leary about side effects he is exercising daily and has a great appetite. It has been 2 mos since diagnosis. Do you think it is a good idea? It was explained to us that it will help keep bad cancer cells from his vessels. Thank you. Debbie Calvert

    • Dr. Demian Dressler on March 7, 2012 at 12:51 pm

      Dear Debbie
      I am sorry you are dealing with oral melanoma.
      not managing this case personally I cannot say if is a good idea or not, but it seems reasonable to me right off the bat. I would of course be doing a lot more…(you have read the Guide, right..??? )

Scroll To Top