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

Why Benadryl For Mast Cell Tumors?

Updated: September 4th, 2019


Vets often prescribe Benadryl for mast cell tumors. Why on earth do they do that? Dr. Dressler explains how this common allergy med can help.

Benadryl for mast cell tumorsBenadryl for mast cell tumors? What on earth does an over-the-counter allergy medicine have to do with cancer?? Let’s find out.

Most of us have heard of Benadryl, the brand name for diphenhydramine hydrochloride. It’s an antihistamine, which means it reduces the effects of excess histamines in the body.

In human medicine, we usually use it for allergies: hay fever, runny eyes, sneezing, and allergic sinus congestion. It is also used for more sudden-onset allergic reactions, including hives, facial swelling and so on.

In veterinary care,  we use it to treat things like insect stings, vaccine reactions or other allergic reactions in dogs.

And we often recommend Benadryl for dogs suffering from mast cell tumors.

Dogs with cancer are not experiencing allergies. So, what’s the logic?

Dr. Dressler goes into deep detail on Mast Cell Tumors in his audio seminar.

Well, it turns out there are similarities between a dog with a high mast cell burden and a dog experiencing allergic flare-ups. And Benadryl for mast cell tumors can address those.

Mast Cells Are Weird and Cool

Mast cells are really interesting cells. They are part of the immune system, a type of white blood cell.

Mast cells help rid the body of foreign invaders or material. They also help in healing. They do this in part by generating a substance called histamine. Yup, the same histamine that we talk about when it comes to allergies.

Mast cells that are normal release histamine as part of their work. Histamine helps attract other white cells to trouble spots, like foreign bacteria, or viruses, or injuries. They’re like those red flags your car’s roadside safety kit has. Histamine “marks” an area of the body that is in trouble, so other immune cells can find the area.

Histamine also causes blood vessels to dilate (get larger), and get a little “leaky.” The increased blood flow brings more white blood cells more quickly, and the little leaks help the white blood cells slip out of the blood and into the area that needs them.

So, you see, histamine is an important part of our immune system.

Mast Cell Detects Trouble ==> Releases Histamine ==> Attracting Other Immune Cells ==> Which Kill Invaders and/or Repair Injuries

So, yay histamine, right?

Yes. Mast cells are cool, because they produce histamine. Until they produce too much.

Mast Cells Can Overdo It

As with all things, balance is needed when it comes to histamine. Too much histamine is not good for the body.

When mast cells release too much histamine, whether during an allergic reaction or by huge numbers of cancerous mast cells, bad things happen.

  • The blood vessels in the area of the mast cells dilate, bringing inflammation and swelling of body tissues. In allergic reactions, this looks like hives and abnormal swelling.
  • The excess histamine is capable of causing the lining of the stomach to produce excessive acid. This causes loss of appetite and lethargy.
  • Blood pressure can be affected if enough histamine is secreted. It can drop to truly dangerous levels as many blood vessels open up all at once.

As it turns out, when a lot of mast cells are busy releasing their contents, they secrete lots of things, not only histamine. There are other chemical signals that work in tandem with the histamine, and those get released, too.

The end result of all these mast cells releasing their chemical signals is that the dog’s body goes into a completely abnormal state.

Inflammation and swelling results, and discomfort, as well. I would imagine the sensation is like getting stung or perhaps old stings (itchy, burning). Those with allergies might be familiar with the feeling of all-0ver discomfort, a sort of panicky itchy weird feeling. I imagine it is something like that for our dogs who have a massive release of histamine.

Histamine and Mast Cell Tumors

Now, both cancerous and non-cancerous mast cell tumors are capable of releasing histamine, and both are capable of releasing too much.

If your dog has allergies, you might see a little swelling or redness, and itching. Same is true if your dog has mast cell tumors.

But NOT every mast cell tumor will release very high levels of histamine that cause terrible symptoms like those above.

So if your dog has mast cell tumors, don’t assume that you will see those symptoms.

Only the most severe cases will have these high levels of histamine release.

Why We Use Benadryl for Mast Cell Tumors

Benadryl blocks the effects of histamine in the body, which is why it’s called an “antihistamine.”

Basically, it helps the body cope with abnormally high histamine levels.

That’s why you might hear your veterinarian recommend it for your dog with mast cell tumors: it can help to block the uncomfortable-to-dangerous effects of excess histamine released by cancerous mast cells.

Benadryl can help with the side effects of excess histamine sometimes associated with mast cell tumors.

Remember how excess histamine can also affect the stomach, by causing extra stomach acid? Benadryl helps with that, too. However, sometimes veterinarians will also suggest using an antacid as well, just to be sure to protect the tummy. Cimetidine and famotidine (Tagamet and Pepcid) are often used, and ulcers (if they are present) are often treated with misoprostol (Cytotec) and sucralfate (Carafate).

Diet Matters

If you’ve read my book, you know that I recommend a low-carb, relatively high fat, moderate protein diet for dogs with cancer.

If your dog with mast cell tumors is also experiencing excess histamine release — and remember, not all do — there are special dietary considerations you should also be aware of. You can read more about special nutritional choices for dogs with mast cell tumors in this article.

Of course, diet is just one of five steps in my Full Spectrum approach to cancer care. In addition to diet, nutraceuticals, anti-metastatic supplements, and mind-body strategies, you can find an entire chapter on the conventional care for mast cell tumors in chapter 30 of The Dog Cancer Survival Guide.

All my best,

Dr D

If your dog has mast cell tumors, this book is a wealth of information. In addition to the main steps Dr. D recommends, read the extra chapter dedicated to mast cell tumors from Dr. Ettinger, his oncologist co-author.


Discover the Full Spectrum Approach to Dog Cancer

Leave a Comment

  1. JLee on October 25, 2019 at 1:50 am

    How do they determine whether it’s grade I, II or III of MCT?

  2. Michelle Potter on August 31, 2019 at 10:48 am

    My dog had a mast cell tumor earlier this year. It was removed and he had chemo because it was a high grade two. Should he take antihistamines to avoid getting more?

    • Dog Cancer Vet Team on September 2, 2019 at 8:39 am

      Hello Michelle,

      Thanks for writing and we’re sorry to hear about your boy. Benadryl isn’t a preventative. As Dr. D writes in the article above, “Benadryl blocks the effects of histamine in the body, which is why it’s called an “antihistamine.” Basically, it helps the body cope with abnormally high histamine levels. That’s why you might hear your veterinarian recommend it for your dog with mast cell tumors: it can help to block the uncomfortable-to-dangerous effects of excess histamine released by cancerous mast cells.”

      But if you are wondering whether to use Benadryl alongside your boy’s current treatment plan, that’s a question best left answered by your vet. They know your dog, and your dog’s current treatment plan, and can make recommendations 🙂

  3. Dottie lohr on August 6, 2019 at 7:44 am

    How much Benadryl can a dog have in 24 hours. He is 75 lbs. and 12 years old.

  4. Sondra Revoy on June 9, 2019 at 6:29 pm

    I just located you scrolling thru google and my tears won’t stop! Bentley, my 10 yr old OES has had these “bumps” inside and on top of his skin throughout his life. It was suggested not to remove them until a procedure requiring anesthesia was necessary. Also the internal lumps have tested benign. You have given me a new direction, for knowledge is strength and everything I can apply to Bentley through your research is a gift from above. Thank you for being here so we could find you

  5. Nat. C on May 26, 2019 at 2:48 am

    Both our regular vet and consulting holistic vet suggested we don’t need to give our dog daily antihistamines, rather continue on his extremely healthy diet and top with a few other things often spoken about for every dog with a MCT.

    Pathology came back with subcut grade 0-1, MCI<1 with clear (albeit narrow) margins. Is this the reason they are not suggesting daily medication?

    We go back three monthly for check up of lymph nodes & earlier if we suspect any new lumps/bumps.

    Thank you.

    • Dog Cancer Vet Team on May 27, 2019 at 10:37 am

      Hey Nat,

      Thanks for writing. Unfortunately, we don’t know why both of your vets are against giving your dog daily antihistamines because we’re not vets, and we don’t know your dog or your pup’s treatment plan 🙂

      In this article, Susan writes, “In some mast cell cancers, large amounts of histamine are released in the body, causing irritation and itching. Most treatment protocols include an antihistamine to help, but many foods either have histamines or trigger the release of histamines in the body — so the diet must be looked at, as well.”

      In the article above, Dr. D writes that “Benadryl may be used to help with the side effects of excess histamine sometimes associated with mast cell tumors.”

      It’s possible that your dog may not be releasing enough excess histamine for your vets to justify adding an antihistamine into your dog’s current treatment plan. But as we’re not vets, we simply don’t know their reasoning.

      However, this is definitely the type of question that you should ask your vets 🙂 Find out why they don’t recommend an antihistamine.

      It’s okay to ask questions! You are your dog’s guardian and you should be made aware of why they do, or don’t, recommend particular treatments 🙂

  6. Leah on May 23, 2019 at 11:16 am

    Can we use Claritin too? Is it dangerous?

    • Nicole on June 13, 2019 at 11:17 am

      I have this question as well. My dog (who now has a MCT) had allergies when he was younger, and we were told that they recommend Claritin for larger dogs (mine is ~65lbs), since it’s stronger than Benadryl. We give him 1/day.

      • Molly Jacobson on June 14, 2019 at 1:56 pm

        Hi Nicole! I’m not a veterinarian, but I’ll jump in with my understanding, which is that the point of using Benadryl is to reduce histamine overload in cases that probably have it (mast cell tumors). Since Claritin is also an antihistamine, I presume that using it to reduce histamine would have the identical benefit. Ask your veterinarian about your dog’s specific case, but my thought is that if he’s already on Claritin as a routine way to control allergies, there would be no specific need to switch to Benadryl.

  7. Dawn on May 6, 2019 at 8:10 am

    My boxer was just diagnosed with grade 2 MCT for the second time. I can not give a high fat diet because she has pancreatic disease. Is there anything else you can recommend? Also, how much and for how long can you give the Benadryl for?

    • Dog Cancer Vet Team on May 6, 2019 at 9:06 am

      Hello Dawn,

      Thanks for writing! In general, the diet that Dr. D recommends in the Dog Cancer Survival Guide can be given to most dogs with cancer. However, it will need to be modified for your dog due to the high-fat content. Your vet will be able to make recommendations on what to include and exclude 🙂

      You may also find this article on Food and Nutrition for Dogs with Mast Cell Tumors to be beneficial 🙂

      Unfortunately, we can’t find any information in Dr. D’s writings on how long to use Benadryl, and what dosage to give your dog. This would be a good question to ask your vet as they will be able to tell you if Benadryl can work alongside your dog’s current treatment plan and at was dosage 🙂

  8. Laurie Mcdougall on March 19, 2019 at 5:40 am

    Hi. I bought Dr Dressler’s book when my “Mikey”, a 10 year old toy poodle was diagnosed with a mast cell tumor. It was surgically removed and luckily came back as level 1 with clean boarders. My vet said no further care was needed. I started making Dr Dressler’s recipe and added the Ever Pup and Apocaps.
    My question is, Mikey was previously on a Urinary So prescription dog food. I still use a little the hard kibble with the Dr’s recipe, is this ok for him since he had stones that he passed without needing surgery about five or six years ago? Thank you! Laurie

    • Molly Jacobson on March 20, 2019 at 4:01 pm

      Hi Laurie! It’s best to check with your veterinarian about diet related to your dog’s specific case. I’m not a vet, but my understanding is that kidney issues usually get a low-protein diet, so you might want to have your vet take a look at Dr. D’s diet and tweak it if it’s necessary. So happy to hear your Mikey had a good outcome, and I think you are wise to be vigilant and make changes anyway. Best of luck!

  9. Jen Green on February 18, 2019 at 3:35 pm

    Hi, please can you advise re the recommended dose of Benadryl? My otherwise healthy 8 year old black lab has had 3 high grade mast cell tumours removed in the last 10 months. She weighs 21 kilos. Thank you.

    • Dog Cancer Vet Team on February 19, 2019 at 8:37 am

      Hi Jen,

      Thanks for writing! As we’re not veterinarians here in customer support, we can’t offer you medical advice. However, we can provide you with information based off Dr. Dressler’s writings! 🙂

      Dr. D answers this question in a previous comment. He writes, “The dose for benadryl is 1 mg per lb, 2-3 times daily, but check with your vet.”

      Please consult with your vet on what the correct dosage would be for your dog, as each dog, their health situation, and their treatment plan is unique 🙂

  10. Gavin Hatton on November 26, 2018 at 11:04 pm

    My name is Gav and I live in the UK my dog has had a mast cell tumour removal 2 years ago and now has 3 bumps appear on his side they have been the same size for a few months but last night became large in about 10 minutes then shrank in about 20 mins would a antihistamine help and how much , I am terrified to take him back to the vets but I know I’ll have to.his name is Ralf and he’s a staffie cross

    • Dog Cancer Vet Team on November 27, 2018 at 8:20 am

      Hello Gavin,

      Thanks for writing, and we understand how terrifying this situation must be for you. We’re not veterinarians here in customer support so we can’t offer you medical advice. However, we can provide you with information based off Dr. Dressler’s, and Dr. Sue’s writings

      As Dr. Sue writes in the article below, if a lump is 1cm or larger, or has been there for over a month, get it checked by a vet ASAP. This might mean getting a fine needle aspirate (or a biopsy in some cases) to determine what the lump is– it’s better to know sooner rather than later. Here’s the link to the article where Dr. Sue goes into more detail on this: https://www.dogcancerblog.com/articles/bump-lump/lumps-on-dogs-when-to-get-them-checked-by-a-veterinarian/

      Consult with your veterinarian 🙂 They know you, and Ralf the best, and will be able to check, and test what the lumps are, and they will be able to provide you with medical advice on what treatment plans/options are available 🙂

      We hope this helps!

  11. […] prescribed for such a thing, but then I read this article explaining mast cells and histamines. Why Benadryl For Mast Cell Tumors? – Dog Cancer Blog There are some interesting comments on the article from people going through this with their dogs. […]

  12. […] can release histamine and cause hives. What you should know about mast cell tumors in dogs: Part l https://www.dogcancerblog.com/blog/wh…t-cell-tumors/ Last edited by Roccosmom; Today at 01:44 […]

  13. Susan Kazara Harper on June 23, 2015 at 8:22 pm

    Beverly, Bless your heart, I know this is hard. Why is she on Benadryl?

    • Beverly Johnson Carroll on June 24, 2015 at 5:36 pm

      She isn’t on Benadryl, I was readying the cancer Vet gives it to take the pain away for cancer, she was on Prednisone; but it made the cancer spread rapid. This is Wednesday night and Thursday morning we will be putting our precious Angel to rest her cancer has progressed so much and she isn’t resp to much. Thank you.

    • Beverly Johnson Carroll on June 24, 2015 at 5:39 pm

      She isn’t on Benadryl, I was taking the advice of the cancer Vet where he said he gave it for the histamine in the cancer. We will be putting our precious Angel to rest on 6/25/15. Her cancer has progressed.

      • Sheila Harris on July 10, 2019 at 4:21 pm

        My 10 yr old dog has had MCT for 2 yrs & we’ve done several treatments including surgery but they can’t get clean margins because it’s on her paw. We do Benadryl & prednisone almost daily but still fighting to keep it down. Is this safe? She’s gained so much weight & seems uncomfortable
        Not sure what to do next??

  14. Beverly Johnson Carroll on June 22, 2015 at 1:02 pm

    My Vet has my dog on prednisone, tramadal 50mg, and antibiotics for now until he knows for sure if she has cancer. She has a large mass on her left breast and a deviated heart. Can I still give her Benadryl? I need to help my baby.

  15. Susan Kazara Harper on November 25, 2014 at 12:33 pm

    Patti, We highly recommend the Dog Cancer Diet, which is in Dr Dressler’s book, the Dog Cancer Survival Guide, as well as at http://www.dogcancerdiet.com as a free download. There are some really good kibbles on the market now, and using them alongside a real-food diet will go a long way toward helping your girl thrive. Personally, I have learned to never assume the cancer is permanently gone… it only take a few cells and my not paying attention for awhile. Better, I feel, to remain vigilant, get the absolute best nutrition and support into my dogs and fill their days will joy and play. Don’t spend days worrying, but stay watchful and make a note of any changes. Take photos on your phone periodically if you think you see any changes. You may want to consider Apocaps, which was designed for dogs with conditions like cancer. http://www.apocaps.com will give you more information about how the ingredients support your dog. We are all sharing the happiness of your good biopsy results… congratulations. Give your girl a hug from our team, and don’t hesitate to get in touch if we can help in any way.

  16. diamondinruff on November 12, 2014 at 7:00 am

    My 3 year old chihuahua mix just had a large mast cell tumor removed from her perinanal area. The biopsy came back as Grade 1 and the vet said there didnt appear to be any spread anywhere. She is on benydryl – he said for the rest of her life. Now, I want to be sure she is eating the best diet for her life. What should I be feeding her? She was eating a good grain-free kibble.

    • Joanna on December 20, 2014 at 9:15 pm

      My izzie had a growth near her private area that took off growing from like a small marble size to the size of a fat cigar about 2 in long. I did not go to the vet I gave her RASPEX I had read about it a few years ago and lots of good reports of how it swank cancer / tumors in animals & left them clear So I thought to try it before going to the vet and I was so pleased. I prayed in Jesus name ,laying hands on izzie & started giving her 2 tabs in am & 2 tabs in pm. In less than 4 weeks it was almost gone. Not selling anything just sharing what I found & how it helped us. Hope this will help you. Lo

  17. Susan Kazara Harper on September 9, 2014 at 3:18 am

    HI Kathy,
    You can ask your vet about trying hydroxizine and mirtazapine- they’re not as effective as benadryl but you’re looking for the best balance for her. Also low dose prednisolone, but all with your DVM in the loop, and your vet is the best one to work with on dosage. I hope this helps!

  18. Katy on September 7, 2014 at 10:20 pm

    Dear Doctors,
    My Pit Bull has MCT. Benadryl makes her so drowsy. Would an alternate antihistamine like Claritin be as effective? What is the recommended dose of both Benadryl and (if indicated) Claritin for a 65 pound dog? Thank you!!

    • Katherine on November 13, 2015 at 2:08 pm

      Benadryl-1mg/lb. My pit just got his biopsy results back, low grade 2. He’s only 4. I’m heartbroken about this. He will now go on benadryl and tagamet for the rest of his life.

  19. Susan Kazara Harper on September 19, 2013 at 5:16 am

    Hi Olive, There’s no way to predict in this format a life expectancy for Lu. It depends on so many factors including type of cancer, staging, whether any other body systems are affected, her immune system, nutrition etc. Your best advisor is your own veterinarian who knows Lu and what she’s been through, and knows you as Lu’s carer. I hope you have read The Dog Cancer Survival Guide and have implemented the Dog Cancer Diet. Nutrition and emotional support are vital. If your vet has prescribed the Benadryl (which makes me think she has been diagnosed with MCT?) then give all of her symptoms to your vet and inquire how you can help her with the nausea. Above all, please don’t focus on “how long does she have’. Make the most of every day and keep Lu happy. She’s living in the moment and is not worried about the future. It’s a lesson we can all take to heart. All the best.

  20. olive on September 16, 2013 at 6:25 pm

    My little Lu is on her second tumor. She’s 7 years old and both tumors have been in the same spot – her neck. This time the tumor is literally directly beneath the scar from her last surgery. I am giving her benadryl twice a day and I give her pepto when she vomits. If she is too active, she vomits and has diahrea. If she has this next surgery, what is her life expectancy???

    • DrSueCancerVet on September 29, 2013 at 3:52 pm

      Hi Olive,
      I am sorry about Lu’s MCT, but remember these are generally very treatable tumors, and one size does not fit all – so no one can tell you thru the web what her life expectancy is.
      I would stronlgy recommend you see an oncologist who can examine Lu, review her records, and make recommendations to find out if the tumor has spread and recommend treatment options.
      Also check out my series on MCT – lots on info there, but see a specialist too!
      All my best, Dr Sue

  21. Cinny on September 9, 2013 at 6:39 am

    My vet also recommended ginger and turmeric caps as supplements to my raw food/probiotic enhanced dog diet, and benedryl when turmors are in early stages of inflammation. We do a few days of prednisone when a tumor is raw and red. This seems to settle the histamines down. My 6 year old boxer has been in great shape for 10 months since he was first diagnosed with stage 2 and had one surgery. I have also added esciac caps.

  22. Michael vaughn on September 4, 2013 at 5:01 pm

    My dog is 13 yrs old and has been getting these tumors of some sort but she busted one and she’s running a fever and acting abnormal. Please reply ASAP

  23. Jacqueline on May 29, 2013 at 12:13 am

    Hi Dr D

    My dog has a small pea sized lump in his skin. We had the needle aspiration done yesterday and it is a MCT. My boy is 10 years old and such a happy dog that I really don’t want to have him operated on (I am also worried about the effects of anesthetic on him as he is a French Bulldog, has never been operated on and has breathing difficulties) Is it possible that the lump may just stay the way it is and have no detrimental effect on his life? I am planning to start him on prednisolone tonight. Am I doing the right thing – or is removal of the lump the best cause of action?

  24. Denise on April 22, 2013 at 7:16 am

    Dear Dr.,
    My 10 year old, Auusie Shepherd, has been developing lumps from his chest to his back legs. He has several on his rib cage and around his leg bones at the shoulder joint. Vet isn’t worried, but his appetite is starting to lessen and he is always ready for a nap. Would the use of the antihistamine possibly work for him?

    • Dr. Demian Dressler on April 24, 2013 at 12:33 pm

      Dear Denise
      my feeling on this is that you should be in contact with your vet about the cause of the bumps. If they are hives (allergic), then antihistamines can help in some cases. But it is very important to determine whether there is an allergic issue occurring, and also why your Aussie is eating less. The bumps may or may not be related to the loss of appetite. That way you can provide the proper care for the actual issue.
      I hope this helps
      Dr D

  25. Kevin on February 28, 2013 at 9:19 am


    We have a 14-yr old female Yorkie-Poo that has a mast cell tumor on her right rear paw (right between the far-right digit, and the next one in). It is quite large and steadily growing. We are working with an oncologist, and she is on chemo; however, it has not worked. The tumor is still growing, although it is currently not bleeding. The tumor is already in her lymph node higher up on her leg. She has her ‘spunk’ and is eating well with no signs of pain.

    We have been given two options: 1.) Surgery to remove either part of her foot, or her entire leg, or 2.) Let her live out her remaining time.

    What should we do? Do people normally have surgery on a 14-yr old dog? Will she survive the pain and healing?

    Or do people normally let her live out her time? What type of phases would a dog normally go through from here on out? When would we know when to put her to sleep so she doesn’t feel any pain (from ulcers, etc.)?

    Thanks for any help or insight into this difficult time.

    • Dr. Demian Dressler on March 6, 2013 at 4:36 pm

      Dear Kevin
      If the conventional options are not working well it would be good to use some other tools. Have you read the Guide yet? I’d be thinking diet, apocaps, low dose oral neoplasene with mirtazapine, possibly palliative radiation…as some first thoughts. You could also consider a different chemo drug (switch from palladia, kinavet,or use the injectable drug protocols etc)
      I would discuss these options with your vet, or for integrative vets perhaps contact the veterinary institute of integrative medicine, or the American Holistic Animal Association.
      Here is another link or two I wrote that might help too:
      I hope this helps
      Dr D

  26. Lakisha on February 23, 2013 at 12:00 pm

    Hi Dr. D!

    Thanks for the helpful information. I have a 7 year old cockpoo that just had a grade 3 tumor removed. My vet referred me to a onologist and she suggested radiation and chemo. The onocologist also did an ultrasound and it seems as though the cancer has not spread. We’ve changed her diet and started her on Benadryl and other supplements. Do you have an other suggestions? Is there more we shold be doing?

  27. Danielle on November 24, 2012 at 5:54 pm

    Our Dog Roxi is a 96Lb American Bulldog. She is all white in color & has alway had allergy problems. She was diagnosed w/ Mast Cell Tumors about 3 years ago. Each day has been different for our girl. One day she is GREAT w/ no bumps, redness or irritation. Other days she will flare up w/ Large (cyst like) bumps all over. Mainly on her hine legs, rear end & belly just under the legs. She has had flare ups before that seemed to go away w/ Benadryl, prednisone & sometimes w/ antibiotics. This time however… She seems like nothing is working. She has been vomiting (which she usually doesn’t do) all day. He belly that has the cysts seems to want to burst open. She has had this happen in the past, but the cyst/group of many cysts is much larger. We recently gave her Echinacea along w/ licoric root. Would this cause her to be upset to in the stomach? We are worried about our girl & just want her to be okay. Does anyone have any advice on how to help her w/ the nausea and or Mast Cells? I’ve called our local vet, but they are out till Monday. Your advice it appreciated! 🙂

  28. maddy on November 8, 2012 at 8:41 pm

    Need to make comment to get newsletter 🙂 Thanks for all the great info.

  29. Nelda on October 3, 2012 at 5:01 pm

    My 10 year old dog Ellie has been to the vet numerous times since July. She has nasal congestion, mucus running from her nose (at times it was bloody) and she just snores and makes all types of noises. We did have her nose scoped and the Vet could not find anything. We have tried many antibiotics and none worked.The vet gave her a Prednisone short just 7 days ago, and it only worked for a few days and now she is back to be stuffed up sounding and mucus running out of her nose.(no blood yet). Can I give her benadryl too? He believes she does have a tumor but we can’t afford to have her checked further. Will the Apocaps work for this? I need help and suggestions guys. My vet of course probably will not recommend anything since we don’t know EXACTLY what type of tumor is in her nose…the prednisone does seem to shrink it when she first got the shot..it just didn’t last. We do know it is the nose since her trachea and everything else looked fine.

  30. Kevin on June 1, 2012 at 6:40 pm

    Type-o : he had the lump for 1 day.

  31. Kevin on June 1, 2012 at 6:38 pm

    The vet has me giving my dog benadryl to treat his nasal-cancer-like symptoms along with prednisone. He’s had 2 nosebleeds, constant nasal congestion and for 1 he had a half-dollar sized lump on his nose. He gets worse when I run out of benedryl and only gets better when I get more. Could it be possible that this isn’t cancer? I haven’t been able to get xrays done because of financial difficulties and because I’m hesitant to have him put under and out of my sight all day while he recovers from the anesthesia. I’m not trying to get my hopes up because hope is a heavy burden for me right now. It’s easier to accept his fate than it is to deal with the ups and downs of hopelessness and denial.

  32. Susan on May 18, 2012 at 1:35 am

    Dr. D.
    I hope my post helps someone. Our 6 year old redhead longhaired chihuahua has had 2 malignant mast cell surgeries. They have been stage 2. After her second surgery, I read about Bendryl and discussed it with our vet. He said to try it. Every morning we give her 2 mg of children’s storebrand Benadryl and so far she has done well. She had surgery about 2 months ago on a suspicious growth, but it was benign which was encouraging.
    Thank you so much for your information!!!!!

  33. Nancy on June 22, 2011 at 4:50 pm

    Hello Dr. D,

    I have a question I can not find the answer to. I have a 4 1/2 year old pug who had a mast cell carcinoma removed from his side in April, 2010. After the first surgery we were told that his margins were dirty and that he would need more surgery, A week later they removed more tissue and we were told that his margins were clean. A few days ago without any notice, he developed hives all over his body and head. His face and snout was very swollen. We rushed him to the vet and they gave him an injection of benadryl and a steroid. We were told to give him benadryl 25 mg 3 more times. Today he seems fine, however, we have no idea what happened, Do you think this could have happened due to a recurrance of the mast cell carcinoma or just some allergic reaction. I do not seem any lumps on his body. The vet that treated him is not our regular vet and did not know his history of the mast cell carcinoma.

    Any suggestions or information would be greatly appreciated

    Thank you.

  34. Cindy on June 6, 2011 at 6:50 pm

    How long should you keep giving the dosage of benadryl twice a day. My dog is close to 100 lbs.

  35. Lisa Richards on February 11, 2011 at 4:10 am

    Dr. D.
    I will get your book, it sounds like it has good information. I had a question if you have time. My 10 year old lab was tested positive for mast cell. We removed bumps. 3 months later more came back. We removed them again. 2 months later tested positive again. Went to oncologist who advised to remove the cancerous bumps and start chemo. We removed them 2 days later, they all came back “negative” for cancer! This third surgery was tough on her and to find them all negative made no sense and doctor couldn’t say why that happened. My dog has been on benadryl, pepcid ac, and prednizone for 4 months. Nothing has returned, they say take her off all meds. Is there any benefit to staying on bendaryl and pepcid ac to prevent it from coming back?

  36. Tammi on November 12, 2010 at 1:55 pm

    Dr. Dressler,
    My dog was diagnosed with Osteosarcoma about 3 months ago. I was wondering if I can give him the Apocaps? He is currently on pred, sucralfate, and tramadol. Thank you for all your research.

    • DemianDressler on November 23, 2010 at 6:29 pm

      Dear Tammi,
      sorry to hear about your dog 🙁
      I use Apocaps routinely in dogs that have osteosarcoma. If you are using pred, cut the labeled dose down to half on the Apocaps. Of course you want to always have your vet involved in any steps in your dog’s care.
      Dr D

  37. Shawn on November 12, 2010 at 12:42 pm


    I brought my 3 year boxer to the vet to look at a small growth on the inside of his ear and wanted the vet to aspirate to ensure it was not malignant. Before the vet tried to aspirate it, she gave him an injection of benadry. What would the purpose of giving benadryl prior to knowing exactly what type of growth it was? Thanks for your help with this.



  38. Julie Marmolejo on November 12, 2010 at 7:57 am

    Dr Dressler

    I have a 10 year old Rottweiler named Misty She was recently diagnosed with hip dysplasia and Cancer in her Back Knee Joint. She is currently on Tramadol 50 mgs for pain twice a day however I have no idea how much pain she is still in and if she needs something stronger? I have some 325mg percocet which I believe is stronger but have no idea if it is safe for dogs and how much she would need, she weighs about 65 pounds. My husband recently lost his job and I cannot afford another vet bill but I’d like to keep her comfortable. She has cut back on eating so I think that might be a sign she is hurting more. Her knee is getting quite swollen probably twice the size of the other knee. I am also at a loss as to how long her go like this before I have to put her down as I don’t want her to suffer too much! I would appreciate any advice you could give me!!

    Please let me what you would recommend?


    Julie Marmolejo

  39. Rachael on November 11, 2010 at 8:23 am

    Dr. D,

    I’m curious how much benadryl you should give for mast cell tumors and for what duration? We have a 7 year old pug who weighs 25 lbs and has been diagnosed with mast cell tumors. A few months ago, we had 6 tumors surgically removed, and at that time our vet did mention benadryl, but did not give specific informtion on dosage or duration. Last night we noticed another small bumb starting to grow, so we wanted to get him started on the benadryl. Could you please help? Thanks!


    • DemianDressler on November 23, 2010 at 6:39 pm

      Dear Rachael,
      I would check with your vet, who knows whether there might be some problem with the benadryl or not. Always work with vet supervision. The dose for benadryl is 1 mg per lb 2-3 times daily, so that would be 25 mg. But check with your vet. I would also suggest Apocaps to stabilize the mast cells.

  40. patsi on October 7, 2010 at 2:14 am

    My Minnie Mouse has been fighting mast cell for over 3 years. I have only had 2 needle aspirations,mainly to prove to the vet that those wart like growths WERE mast cell. I have removed over 14 small growths,have several in a jar,but I haven’t been able to reach all of the original ,larger tumor,thought I had it but after a year it came back. I have found another weapon tho,lutimax(strong luteolin) the tumor that came back has shrunk to about 1/3 of it’s size,I am giving 3 per day,using benedryl & tagament(has anti cancer properties). I am not sure how it works,please Dr Dressler,expound a little on this lutimax for us,I am very excited & Min is feeling better. Her first treatment was Aug. 1,2007,so it has been a long fight,overall tho,good QOL 🙂

    • DemianDressler on October 13, 2010 at 4:43 pm

      Dear Patsi,
      great question. Luteolin can benefit dogs with mast cell tumors in my experience, as you have found as well. I am glad it is helping your Minnie Mouse! It is for this very reason that I included it as one of the compounds in the formula created for my patients (Apocaps), in addition to other potent compounds that have shown to act with luetolin to help these dogs. If you would like to read more about lueteolin specifically, check out this post. and this one too.
      Dr D

  41. DemianDressler on October 6, 2010 at 5:43 pm

    Dear Harvey,
    Thanks for your comments. Benadryl can help decrease the effects of the histamine which is produced by the mast cell tumor, and is definitely a good idea. I should make clear that it does not stop the cancer from spreading though…But thank you for your kind words and I am so sorry for little Roxy.
    All my best,
    Dr D

  42. Nicole Pinckard on October 6, 2010 at 1:30 pm

    Hello, we are proud to have an 8 year old Blue Nose APBT. We saved her life by adopting her from the pound. Six years ago we had 3 large tumors removed one of which came back 6 months ago. They were found to be mast cell one being a stage 4. A few months ago a few more came back and we also had thos removed. Since then no more have shown up, my concer is that I want to know whats happening inside her. She eats like a pig and still loves to run and play. She does suffer from arthritis and I would like to know how to treat that without upsetting her stomack. Thanks for all the helpful information and I’m so sorry for the Harvey’s loss of their beloved pet.

    Nicole Pinckard

    • DemianDressler on October 13, 2010 at 5:19 pm

      Dear Nicole,
      you raise a very good point. Dogs with cancers like your dog’s should have regular ultrasounds done to assess the internal organs, with blood and urine testing, every 2-4 months as directed by your vet. Please be sure to have your vet supervise all of your dog’s treatments. In my patients I prescribe Apocaps. I would really pay attention to her diet (you can download the Dog Cancer Diet pdf on the top of the blog page). Finally, there are many other things to consider (so many that it filled a book), so I would really take the time to get and read The Dog Cancer Survival Guide. It is easy reading and will help a lot.
      Dr D

  43. Donna Walker on October 5, 2010 at 3:09 pm

    Harvey, I am so sorry to read about your tragic fight with Roxie. My Husband and i had a similar situation with our 5 1/2 year old Golden Retriever named JOSIE. Our fight began in May with her first operation and a second one in the beginning if June. The vet didn’t aspirate the 3 tumors so he didn’t know that he was removing mast cell tumors. Three weeks after her second operation we went to an oncologist who gave us the horrible news that Josie’s cancer had spread to the lymph nodes and we had little time with her. She died August 19,2010. Just 54 days after the oncologist informed us of her grade three mast cell cancer. Our vet did not tell us that her cancer was deadly and we lost some valuable time in the beginning and were literally online gathering information day and night to fight or slow down the progression. It’s a shame that there is nowhere we can go to receive the correct protocol for this cancer.I learned of the Morris Animal Foundation after my Josie was gone. Hopefully someone reading this can pass the name along and help someones pet. They do alot of research on Canine Cancer and help sponsor fundraisers for research dollars. Again, I am sorry for your loss! Donna

  44. Harvey on October 4, 2010 at 2:33 pm

    Dr. Dressler,

    You are so right in the use of Benadryl involving a mass cell tumor. My 12 year old Pug named Roxie had a growth on her side 2 months ago. My vet sent me to a “special” vet hospital for the removal of the growth. They removed the growth then tested it finding it to be a mass cell tumor. Within a two month time period the tumor came back 5 times the size with other tumors also appeared on her body. Soon she started to cough alot and was in great pain and the tumors started to bleed.. She was a sweet loving animal and she lost her fight on 10/04/10. While reading up the causes and treatments for mass cell tumors I found out that the “special” vet hospital NEVER gave my dog any type antihistamine prior to or during the operation. The operation acted like a bomb sending the cancer through out my poor little girl. The information you provide to your readers is very imformative and helpful, I just wish I found you 2 1/2 months ago. But I do have two other pets at home, a boxer and another Pug so thanks to you I am better prepared in case this horrible thing happens to then. So all you other pet owners out there please speak up for your animals, ask the vet questions and take them to a CANCER VET Hospital. Just don’t think your vet is a “Jack of all trades” and knows how to treat cancer.

    Again Doctor thank you!


  45. Susan Hickman on September 16, 2010 at 12:14 pm

    Hello Dr Dressler,

    I hope you won’t mind but I have another question. I have been reading a lot about Benadryl & MCT. When giving the Benadryl tablets should you also give something like Zantac or Pepcid as well. Tagamet is not available OTC in the UK.

    Many thanks


  46. Susan Hickman on September 14, 2010 at 11:05 pm

    Hello Dr Dressler,

    My dear Golden Retriever Penny has mast cell tumours. One was removed in 2008, another 6 months ago.Two nights ago without any warning another erupted & busts needing emergency surgery. Whilst she was under the anaesthetic the vet took the opportunity to remove 2 more that we had been wtaching for months as well. I have read with interest about Benadryl. I want to start Penny on it. My vet was not very encouraging & pretty negative about it but I feel more that it was because it was my suggestion & not his ! He has told me to give her one in the morning & one in the evening. Please would you advise me on this . Many thanks

  47. Cindy on August 3, 2009 at 5:22 am

    Hello Dr Dressler–

    I have an 8 yo female lab/redbone mix. She has had a medium sized lump on her belly area (near her nipples) for a little over a year. It has not changed in size and she as no related symptoms (appetite is fine, no itching, no vomiting, no pain. She is as happy, hungry and loving as she has ever been!). I was recently told it was a mast cell tumor. Due to recent divorce and job loss, I cannot afford the surgery to have the tumor removed. Are there any alternative options or suggested treatments other than surgery–should I be giving daily benedryl… if so, how much? What should I expect if I am unable to treat this tumor?



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