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

Why use stomach medication for mast cell tumors?

Updated: January 15th, 2020

Many dog lovers are coping with a diagnosis of canine mast cell tumor.  Just yesterday afternoon I was removing a very large one from the body wall of Big, a 10 year old, 105 pound, much-loved mixed breed.

The day before his surgery, Big started to throw up.  He became quite sick, and would not eat.  His tumor, which was about 5 inches in diameter, had started getting very painful, red and inflamed.

Luckily, tumor is now out and Big is on his way to happier days.

One of our strategies is to help Big with his nausea.  I was explaining to his owner last night that the mast cells in the tumor secrete a substance called histamine, which is the same stuff that causes a bee sting to become red, swollen and painful.

These high histamine levels now in Big’s bloodstream cause the lining of the stomach to produce excess acid.  When you have a belly full of acid, it feels awful and you may start vomiting.

So in dogs with any signs of decreased appetite, nausea (licking lips a lot, salivation), vomiting, or loss of energy with mast cell tumors, we always want to address this acid issue.

There are several approaches.  We definitely want an antacid.  Cimetidine (Tagamet) is a good choice, as this drug has not only antacid effects but also some nice, documented anti-cancer effects.  Tagamet is available over the counter at most locations where non-prescription human medications are sold.  Like many drugs we use in veterinary medicine, it is labeled for human use.

Fresh ginger is always a nice supplement to use in dogs with nausea, and has been shown in papers to help in human medicine with both anti-cancer effects and helping nausea. Many big-box grocery stores will carry ginger root, and some health food stores do as well.

For more information on Mast Cell Tumors, get a copy of the Dog Cancer Survival Guide

Many clinicians advise famotidine (Pepcid), which has a good antacid effect, but no anticancer effects.  You can get Pepcid AC over the counter at most places where non-prescription medications for people are sold.

In cases where there is no other option and the vomiting is very severe, a drug called Zofran (odansetron) can be used.  It is rather expensive, and its use is on the new side.  It does help though for cases where the stomach upset is really bad.  It is a prescription medication.

If there is diarrhea, which reflects inflammation of the intestine (lower down the digestive tract than the stomach), misoprostel (Cytotec) should be considered.  This drug stimulates the protective lining of the intestine and decreases inflammation of the intestinal wall. This is a prescription medication.

Slippery elm, which is from bark of the slippery elm tree, is a good supplement that can be added for diarrhea as well.  It acts as a natural bandage, coating the lining of the intestine and helping soothe and heal.  Slippery elm is available on-line and at health food stores.

Branched chain amino acids can also be added as a part of the arsenal.  These supplement the other approaches by providing the building blocks to rebuild the lining of the intestine.  Branched chain amino acids are available in health food stores and supplement outlets.

Probiotics can always be added to help a bit with diarrhea.  A probiotic is a bacteria which helps restore the normal amounts of healthy bacteria in the intestine.  We need these bacteria, and so do our dogs. These can be purchased at supplement outlets and health food stores.

Lastly, plain old liquid Pepto Bismol helps a lot with diarrhea as well, and is available over the counter too.

For more information and specifics on these items, you can find more details on dosage and use in The Dog Cancer Survival Guide and through discussions with your vet or oncologist.

All my best,

Dr D


Leave a Comment

  1. Nick P on April 25, 2011 at 9:34 am

    My daughter’s Chihuahua was diagnosed with a singular mast cell tumor. Her vet put him on cimetidine only and after two months the tumor is gone according to the vet. Can this be? She to reduce and then eliminate the cimetidine and then that’s it. I cannot believe this cured the pup. Is it possible?

    • DemianDressler on April 27, 2011 at 10:20 pm

      Dear Nick
      well, i believe that it may have shrank to be imperceptible…but I wonder how the diagnosis was reached…and also we need to understand that mast cell tumors can indeed come and go based on the histamine release waxing and waning and thus the swelling going up or down…time will tell!

  2. jess on February 1, 2011 at 12:08 am

    Dr Dressler:

    My Boxer Scarlet is not doing very well but, I am trying to be patient. After getting your guide and trying to have a better care plan for her. I am using the apocaps and I am following your guide. She is taking benedryl and tagemet, 1 pedisone a day and currently she is on an antibiotic because the ulcerated mass on her front paw seems to get infected on and off. I am going to the oncologist wednesday, I am going to ask her about predsolone being injected into the mass cell on her paw to see if it will shrink. There is also a lymp in her shoulder, I mentioned in my last e-mail that is the size of an egg. It has started to ulcerate. Is it safe to also inject with predsolone in this mass also or is that impossible? I Thank You for the wonderfull guide that has helped me to relax a little and try to understand how to help my best friend!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
    Any information you could suggest would be greatly appreciated.


    • DemianDressler on March 8, 2011 at 9:49 pm

      Dear Jess,
      so sorry to hear about Scarlet. I wonder why no removal of the growths? Surgery is still one of the main ways we get rid of tumors in dogs and it seems like this would be a good idea, along with biopsies, after some initial tests.
      I hope the oncologist consult went well
      Dr D

  3. margaret on January 7, 2011 at 5:10 pm

    I’m so sorry for you heartbreak. I went thru this last oct. with my 10 year old Shih Tzu, Tommy. It was a long and hard road and ended in sorrow for all involved. I think you have covered all possible options looking for cure or at the least some more time. Tommy started with the mast cell tumor on his front paw. We had the surgery and then in Jan started with radiation. During this process the mast cell tumor moved from the paw site to the lymph system and developed a large growth in the side of his neck. We had three drs. working on the problem including a holistic dr. Tommy had 14 months before he passed.. most of it good some bad. Would I do it again?? you bet.. I miss him everyday.. margaret.

  4. jess on January 7, 2011 at 12:57 pm

    Dear Dr. Dressler:

    As with alot of the other dog owners, I am a Boxer/dog lover whose dog Scarlet has a Mass Cell tumor on the front paw along with lymp spread in upper shoulder the size of a large egg. This is not the 1st Boxer of mine this has happend to, this is the 3rd one in less than 2 1/2 years.(2 other females died of different types of cancer it has been quite life changing). She is currently being treated with benedryl, predisone, cycblastin (spelled this chemo wrong hope you can identify), pepcid and recently the growth looks to be spreading but, it is hard to tell if it is inflammed because it changes drastically from day to day. We are treating her also with hollistic, flax oil, mushroom, shark cartilage so much it would be hard to list she is 6 yrs old and blood tests say she is tolerating well, she is grade III. Would it help to change the pepcid to tagemet ? These growths I was told by 2 onclogists could not be removed but, I am hopeful she might be a fighter and if I do everything possible there might be something I missed or could try. If you have any suggestions please HELP, I am running out of money and information. I have read your helpful advice and any would be greatly

    Thanks, Jessica

    • DemianDressler on January 13, 2011 at 10:35 am

      Dear Jessica,
      so sorry to hear of these hard days. One thing that I notice is that the supplement selection appears to be less than ideal. Have you read The Guide? It is an easy read and will answer questions about diet (very important), proper supplementation, immune support, and ways to modify brain chemistry to shift to a cancer-fighting state. Are you not using Apocaps (the apoptogen supplement I use for my patients)? Beta glucans? Doxycycline/cimetidine? These are some of the ideas right off the bat.

  5. Diana on September 13, 2010 at 3:10 pm

    I had to make the devastating decision to euthanize my dog Mickey this past January after he had surgery to remove a bladder stone. He was 11 yrs. and 10 months old and had diabetes. He had just been switched from Vetsulin (which was no longer available) to NPH insulin just 3 days prior to having his surgery. He developed ketoacidosis and was very sick for 5 days. The vet gave him barium to try and soothe his esophogus and stomach which was full of ulcers because he said he had found in the past that the barium could actually help stop the vomiting and ease the pain he was experiencing. When he was still vomiting the next day the vet took some x-rays and discovered a “filling defect” in the stomach where the barium could not pass through. He told me that Mickey had stomach cancer and that there was nothing we could do for him. Mickey did not have any signs or symptoms of stomach cancer before his bladder surgery, just occasional vomiting. The vet later told me that he was not sure if Mickey had cancer because he did not do an autopsy. I am devastated and feeling so guilty for putting him down!! Could this really have been cancer or do you think he developed some kind of blockage after his surgery? I miss him soooo much!!

  6. Anne on October 20, 2009 at 3:39 am

    Thanks again Dr. D,
    We are seeing the vet tomorrow, and I will ask. She crashed again last night, exactly a week after her last crash, so your cyclic histamine theory must be right on the mark. I appreciate your input. Even with two excellent vets in the mix, you’re still offering new ideas when they seem to be running out of them.

  7. Anne on October 19, 2009 at 6:33 am

    Thanks Dr. D,
    I appreciate your reply, and hope you can clarify about the antacid component. She was on Pepcid, but was switched to Prilosec by the oncologist. How does that fit with the Tagamet? Does it act with Benadryl? Does it make sense to mix and match antacids, or should we pick one? She also has Ondansetron for nausea, a drug (Sulfa-something)for ulcers, a small dose of Prednisone and Cipro. She is on Hesperiden, which I think gives her the luteolin you recommend, Milk Thistle for her liver, and now Benadryl. Tramadol and Gas-X as needed.

    • Dr. Dressler on October 19, 2009 at 11:14 pm

      Anne, I would discuss doxepin with your oncologist. This is the real deal for histamine receptor (very potent H1 and H2) blockade. If they don’t know about it have them research it. Known a little in behavioral circles as an “anti-depressant” but there is way more to it..

  8. Anne on October 15, 2009 at 7:53 am

    Has anybody had this experience? My 11-year old dalmation has been battling mast cell disease since last winter. She’s had surgery, chemo and even Palladia, but it still spread. A month ago, her white count was way down, the disease showed up in her liver, and they told me it was time to let her go. Three days later, she rebounded so well that I began to doubt the test results. Now it’s just a roller coaster. She crashes, she bounces back. She’s curled up in a ball shivering, she’s bouncing around like a puppy. She’s on all these stomach medications, plus antibiotics, Benadryl, herbal supplements and Metro-something for a nasty bout of diarrhea that hit a few days ago. She recovered in less than 24 hours. The oncologist doesn’t seem to know what to do with a dog that’s past her expiration date, and her holistic vet is stumped too. Is this this just the way the disease progresses? I am beyond grateful for any extra time with my girl, but I could really use some advice on stabilizing her. I appreciate any feedback. Also wondering the same thing as Lu Ann re: anti-histimines. Thanks!

    • Dr. Dressler on October 17, 2009 at 9:58 pm

      Anne, I would bet the cycles are related to cyclic histamine secretion and gastric (stomach acid) secretion. Definitely talk to your vet folks about increasing the antihistamines and cimetidine/famotidine, and possibly some pain medication for those episodes. Consider luteolin too, which in humans has been shown to stabilize mast cells and inhibit histamine secretion.

  9. Lu Ann on October 9, 2009 at 12:44 pm

    Reading through all the information, I didn’t see anything about using an antihistamine on the mast turmors. Your article said the tumors produce histamine and that’s what causes them to become so large. Is it likely that an antihistmine will help? I am giving my Pepto Bismol right now and will start her on Pepcid in the morning, but wanted to know if we could use the antihistimine. I’m hoping to shrink the tumors enough that she can start eating again and have surgery to remove them.

    • Dr. Dressler on October 17, 2009 at 9:54 pm

      Lu Ann, the treatment for mast cell tumors involves a lot more than this single post about digestive upset and mast cell tumors. Yes, benadryl is commonly used to deal with histamine secreted by mast cell tumors. Interestingly,the cimetidine in this post is a specific type of antihistamine, but works on a different receptor type than does benadryl..and deals with stomach acid, unlike benadryl.
      Best, D

  10. Gayla Stone on October 6, 2009 at 7:30 am

    I have heard that mast cell tumors typically can spread to other areas of the body. My golden had a mast cell and it was surgerically removed and we were led to believe she would be ok because the vet said he got the entire cancer. The cancer spread to other areas of her body and she died of the disease. Should we always do surgery and hope for the best or are we just kidding ourselves?

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