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Featuring Demian Dressler, DVM and Susan 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



 

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  1. Linda on February 10, 2019 at 11:13 am

    My 8 yr dog 2 yrs ago mast cell tumor low grade 3 removed and been in Chinese herb w Benedryl and famotadine. Recently he had a cluster of seizures for a few days and now on Kappra. I have been cooking the full spectrum diet mixed w high protein low carb kibble. If I make base mix with flounder/cod do I need to supplement recipe with additional omega 3 oil and cottage cheese?
    It seems that there is not a diet formulated for seizure dogs either. Your duet is the most healthiest even compared to the keto.
    Thank You Linda

  2. Vicki Malick on September 6, 2017 at 5:53 pm

    My older female beagle has a red lesion on her upper lip bigger than a pencil eraser. What could it be?

  3. Diana Loken on August 31, 2014 at 12:09 pm

    Dr. Dressler,
    My 9 yo female Chihuahua developed a lump on her right ear lobe earlier this year. Her vet removed it along with the majority of her ear and had it biopsied. It was determined to be a Grade III MCT. Unfortunately, it was also determined that the margin around the removed tumor was dirty. We were told this type of tumor is very unpredictable and may or may not grow back. In less than a month after the surgery, a pea size tumor was back on what remained of the ear. My daughter took her back to the vet on a Wednesday morning and was told we could take her to a specialist to have the remainder of the ear removed along with a large amount of surrounding skin. She could then have radiation. My daughter was told there was still a high potential of growing back and spreading microscopically. The vet told her the growth could be so rapid that we could wake up in the morning and the pea size could be golf ball size. We were told to treat her with Benadryl (1/2 of a 25mg pill 3Xdaily) & Pepcid (1/2 of 10mg pill 2Xdaily) to counteract the release of histamine. Friday morning the tumor had grown to just under golf ball size and is now also on her neck below the ear. I called the vet and was told if we don’t choose to immediately subject her to more surgeries and radiation, to watch for further symptoms. These being vomiting, lethargy, excessive sleeping, and anything else that isn’t characteristic to her. And I hesitate to put her through radiation because my brother had it earlier this year for treatment after having surgery for esophageal cancer. They had to stop the treatment because it was killing him. I’m afraid to put her through the agony my brother was enduring and making her final days unbearable. She still scratches the area when I’m not home until it’s bloody. Is there a cream I can apply to it in addition to the Benadryl for the itching? Is there anything else I can do to relieve the itching and discomfort she seems to be experiencing?
    Any advice will be so appreciated! I love her so much and want to do whatever I can to keep her happy and comfortable.

  4. Diana Loken on August 31, 2014 at 8:31 am

    Dr. Dressler,
    My 9 yo female Chihuahua developed a lump on her right earlobe earlier this year. Her vet removed it along with the majority of her ear and had it biopsied. It was determined to be a Grade III MCT. Unfortunately, it was also determined that the margin around the removed tumor was dirty. We were told this type of tumor is very unpredictable and may or may not grow back. In less than a month after the surgery, a pea size tumor was back on what remained of the ear. My daughter took her back to the vet on a Wednesday morning and was told we could take her to a specialist to have the remainder of the ear removed along with a large amount of surrounding skin. She could then have radiation. My daughter was told there was still a high potential of growing back and spreading microscopically. The vet told her the growth could be so rapid that we could wake up in the morning and the pea size could be golf ball size. We were told to treat her with Benadryl (1/2 of a 25mg pill 3Xdaily) & Pepcid (1/2 of 10mg pill 2Xdaily) to counteract the release of histamine. That Friday morning, the tumor had grown to just under golf ball size and is now also on her neck below the ear. I called the vet and was told if we don’t choose to immediately subject her to more surgeries and radiation, to watch for further symptoms. These being vomiting, lethargy, excessive sleeping, and anything else that isn’t characteristic to her. I hesitate to put her through radiation because my brother had it earlier this year for treatment after having surgery for esophageal cancer. They had to stop the treatment because it was killing him. I’m afraid to put her through the agony my brother was enduring and making her final days so miserable. She still scratches the area when I’m not home until it’s bloody. Is there a cream I can apply to it in addition to the Benadryl for the itching? Is there anything else I can do to relieve the itching and discomfort she seems to be experiencing?

    Any advice will be so appreciated! I love her so much and want to do what I can to help her without taking away her quality of life.

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