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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. Leslie D Ufford on September 28, 2009 at 7:40 am

    I couldn’t attend the Webinar but I just finished listing to it. You addressed my question (Leslie Parker for some reason you got my first name and town name). Clear margins were not obtained because of the location. His tumor was in the axillary region and there were so many vital structures in that area. There is no evidence of spread at this time. My gut feeling was the same as yours, use everything, but I think that the holistic vet is concerned about long term effects of the Cytoxin. Do you think we should try again with surgery even though the location is risky. The original surgery was not done by the oncologist but in a large, progressive hospital. I just don’t know if the were conservative because they did not know what the tumor was or if the structures were truly the issue. The fine needle aspirate done presurgically was mostly blood with no definative diagnosis. The surgeon actually expected the tumor to be a different type. My dog currently shows no evidence of disease. He had had xray, ultrasounds, bloodwork and physical (palpation of area) exams.

  2. christina on September 28, 2009 at 1:52 am

    Dear Dr dressler,
    unfortunately I have a second Italian greyhound with mast cell cancer. While Donny was going through radiation, I found a tiny lump on marcelino’s side (under the shoulder) We had it taken out (it was too tiny to aspirate) My vet was concerned about the chance for it to ba a mast cell cancer because the lump rose and fell over and over for about a week.He told me about the Histamine they give off. He removed it and it turned out to be a mast cell grade 2. He got good clean margins but wanted to go back in a few days later and make even more of cleaned area because of what my other IG went through with him
    needing radiation. We did the stain kit (he was the one who took it upon himself to send out for the stain :)) it came back that the reocurrence of the mast cell was very low (sorry, don’t remember the terminology or #s) Based on the kit, the lab gave marcelino about 70 months before we would have to worry about cancer. No radiation was given and no chemo. NOW marcey has a second growth about 3 inches from the center of the first. It was so tiny, you could hardly see it but then it would grow to the size of a golf ball within an hour and then after a dose of benadryl, it would shrink again. This has been going on for 2 weeks and his surgery to remove it is set for tomorrow. We have not had it aspirated and now it is so tiny. I am opting for radical surgery and do not want to put marcey through 2 surgeries again because I know it has to be a mast cell again. Am i wrong? Should I just have it popped out, tested and THEN do the radical surgery given his history??? The last surgery was only a few months ago. i know my vet is aware of doeing with the benadryl during mast cell removal….but maybe some cells slipped by, causing this second tumor so quickly???
    This dog also had oral resorptive lesions that took away ALL but one tooth before he was 3 years old. He is now 5 and only has one upper canine left. He is a rescued dog so i do not know his breeding history. He is a strong and healthy dog and is fed Dr Harvey diet since he was 5 months old. His teeth (when he had them) were brushed every day– that is why i noticed his teeth turning pink and caught the mouth disease so early. (I am teeth obsessed) He had 4 surgeries in 2 years as the teeth succumbed to the lesions.

    I am petrified that my IG is full of cancer cells due to his immune issues…I do not vaccinate either.
    this was his last tooth surgery——and his mast cell tumor is also on this same site.

  3. christina on September 27, 2009 at 12:45 pm
    • Dr. Dressler on September 27, 2009 at 1:04 pm

      Thanks for the useful input Christina. Good for Donny boy!
      Dr D

    • hundetrainer saarland on September 13, 2012 at 3:15 am

      I’m still learning from you, as I’m improving myself.

      I certainly liked reading everything that is posted on your site.

      Keep the stories coming. I enjoyed it!

  4. christina on September 27, 2009 at 12:44 pm

    thank you Dr Dressler for such a fine book. I purchased it while my Italian greyhound, Donny, was going through radiation treatment…boy I wish I could have read it BEFORE I decided so lightly to go through with the radiation! Your book explains everything so easily…my top oncologist did not 🙁

    my poor donny took over 4 months to heal from the horrible burns he received from the radiation. He had a delayed reaction to the treatment. Went through 17 rounds with no issues, no pain, no hairloss…………THEN bam! he was basically writhing in pain with burned skin UNDER his coat! the photos are horrific. The radiation doctors told me that what he had was a very rare reaction.

  5. Katie on September 25, 2009 at 9:46 am

    Ron, I’m sorry for your loss, but I can’t imagine that it’s Dr. Dressler actually deserves the treatment you describe. Do you really think it’s his fault that your Bichon passed? I have read his book, implemented his recommendations, and while my Sweetie is not out of the woods, I can see that she is really helped. I also attend Dr. Dressler’s monthly teleseminar and get all of my questions asked. I don’t think it’s fair for you to assume that if you post on a blog where hundreds of others post, too, that Dr. Dressler can answer every question personally. Again, I’m sorry for your loss, because I know exactly how it feels (my Dusty passed last year from Mast Cell), but I think you’re letting your anger get in the way. I for one am thankful that Dr. Dressler’s information is here, now, to help my dog. The fact that I didn’t know about him last year doesn’t mean that he’s to blame for Dusty dying. I hope that eventually you find comfort, because I know how hard it is to lose a great dog.

  6. Ron on September 25, 2009 at 8:06 am

    I asked for this information several months ago when I had a Bichon with stomach cancer and didn’t get a reply. Thanks for nothing. My dog is dead and your information is 4 months to late. If you caught on fire I wouldn’t piss on you to put the fire out. Now you know how I really feel.

  7. Katie on September 24, 2009 at 2:12 pm

    Since my dog is raw fed he dosent seem to be affected with the over production of acid when histamine releases with mass cell. Since Dannon is eating Raw foods I believe this helps to disperse the excess amounts of HCL that may be produced and the body uses it for digestion the way dogs are supposed. There food is digested in the stomach instead of the small intestine like canned and kibles are not the way nature intended it to be. Even with Neoplasene. NO vomitng no diarrhea no loss of appetite. So far so good. Next is angiostop, myomine and revivin for cancer apoptosis. This is the next rotation for treatment as well as DMSO mixed with sodium bicabonate as a poltis to rid the body of the external tumors. And yes it really works. Or it can be injected directly into the tumor especially if the sodium bicarb mixture is injected corectly. The tumor shrinks and disapears completly, typically in 6-9 days. These are alternative therapies that can help and rid the body of cancers.

    • Keven Bonner on September 24, 2009 at 2:18 pm

      Hello Dr. Dressler,
      Our doggie had squammous cell carcinoma of the nasal septum. Dr Alice Villalobos, Oncologist, prescribed Reglan before each intra lessional treatment. Do you use this medication in your practice?

      • Dr. Dressler on September 27, 2009 at 7:27 am

        Reglan (metaclopramide) is a common medication used to control vomiting. Yes, I have used it. I will talk more about the treatments for nausea on the webinar this week (, which will be recorded if you want to listen later. Thanks,
        Dr D

  8. Carmen on September 24, 2009 at 7:06 am

    Dear Dr. Dressler,
    Thank you for this very informative and helpful information. I was treating my Boxer with an antiangiogenesis protocol that was very upsetting to his stomach. At the time, I used a generic form of Pepcid AC but am very thankful to know that cimetadine has anti-cancer benefits. Since Boxers seem to have sensitve stomachs from time to time, I will defiantely use this instead when needed.

    Thanks again!

    • Dr. Dressler on September 27, 2009 at 7:39 am

      Thanks Carmen. Best of luck to you and your Boxer. You may be interested in this month’s webinar on mast cell tumors (, which will be recorded.
      Warm regards,
      Dr D

  9. Janet on September 24, 2009 at 4:34 am

    Hello Dr. Dressler,
    We have a boxer the we have been giving our dog Pepcid for awhile now because he will occasionally vomit when he drink a lot of water at once and he seems to get an upset stomach easily. He has had four mast cell tumors all which have been removed. They were all send off to Michigan State for c-kit testing. Three came back with a Kit staining pattern 1 and one came back as a Kit pattern 2. All were PCR negative. Now we are being told he needs to have chemo which I am fine with if it is necessary but he is only 4 years old and we can’t seem to get a really good reason as to why we should do the chemo. He is healthy now that the mast cell tumors are gone. I was just wondering what your thoughts would be. We give him krill oil and feed him Orijen 6 fresh fish with sea vegetables which seems like a good food. Do you have any syggestions for us that might help?

  10. Kate on September 22, 2009 at 4:45 pm

    Hello Dr. D,

    Thanks for all the useful information. I didn’t know that fresh ginger can be a nice supplement that can be used to ease dogs in nausea.

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