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

Mirtazapine for Dog Cancer

Updated: May 15th, 2024

Dear Dog Lovers,

A newer drug is being used frequently lately, and I would like to make sure everyone dealing with a canine cancer diagnosis has heard of it.  This medication may help some dogs out there, so let’s keep everyone up to date.

The drug is mirtazapine, also called Remeron.

Now granted, many of the readers of this blog want to know about diet and supplements.  In the spirit of true integrated (full spectrum) medicine, we should look at everything conventional science has to offer, hence this post.

But for those who want to know what supplement I use in my patients, here is the quick answer: Apocaps.  And yes, of course I am biased since I put it together and use it.  It is not a nausea medication, rather it helps to normalize a critical process called apoptosis in the body.

Mirtazapine is a very effective appetite stimulant.  This is particularly useful in cases of canine cancer, especially if either chemotherapy or the cancer itself is causing a loss of appetite.

On top of this, it helps with nausea and vomiting, and helps block spasm of the muscular wall of the stomach and intestine.  This is useful as it not only improves nutrition by keeping food down, but on top of that, alleviation of vomiting is a major life quality positive.

But there’s more.  Mirtazapine has a neat little antihistamine effect.  Dogs with mast cell tumor cells in the body often have histamine excess, since the tumor cells secrete histamine.  Too much histamine is not good for the body, causing swelling, redness, discomfort, nausea, vomiting, loss of appetite, and even low blood pressure. This makes mirtazapine very well suited for some dogs with mast cell tumors.

Finally, this medication is an antidepressant.  Although there is little talk of canine depression’s link to cancer, there are some documented links in human medicine.  In my opinion, the same reasoning may be applied to dogs, being sentient beings with happiness and sorrows like ours.

Mirtazapine was originally designed and intended for use in people for its antidepressant effect.  However, in veterinary cancer care, we take advantage of mirtazapine’s effects on fighting nausea and helping with appetite. The effects on mood and anxiety are a bonus!

Mirtazapine works by increasing two chemicals in the body, serotonin and norepinephrine.  A few other drugs also increase the levels of serotonin in the body.  If these effects add up, a reaction can occur.  Some other drugs that may significantly  increase serotinin levels are Prozac (fluoxetine), Anipryl (selegeline), and Elavil (amitriptyline).  You should double check with your veterinarian if your dog is on these drugs already, and you have a prescription for mirtazapine.

For more information on topics like this, check out The Dog Cancer Survival Guide.


Dr D

Leave a Comment

  1. Angela A on January 31, 2012 at 7:02 am

    Our 16 year old jack russell was diagnosed with a tumor on both her liver and her heart 2 years ago. I am a pharmacist, and after doing some research on my own, put her on AllerG3 supplement, which contains a blend of antioxidants and omega 3 fatty acids. Omega 3’s are important in suppressing tumor growth, whereas, I have read omega 6’s can have the opposite effect. After being on it for 1 month, she showed a dramatic improvement. We then took her to an alternative med vet, who prescribed Wei Chi Booster, a chinese herbal, for her, and we continued to give her the AllerG3. We elected to do alternative therapies for our dog because the tumor on her heart made her high risk for any kind of surgery. We could not do any kind of chemotherapy because without doing biopsies of the tumors on her liver and heart, there was no way for the vets to know what kind of tumors/cancer she had, and thus, no way to know what chemotherapy might possibly be effective. At the time she was diagnosed, the soft tissue specialist told me, best case scenario, she would probably only live 6 months, but maybe only a couple of weeks. We were devastated. Today, however, 2 & 1/2 years later, we are thankful for every day we have had with her. We did stop giving her the Wei Chi Booster about 6 months ago, because she was refusing to eat her food with it in there, but we continued the AllerG3. Unfortunately, she was just recently diagnosed with glaucoma in one eye, and congestive heart failure. The ER vets put her on lasix and vetmedin for her heart, but the vetmedin has left her with no appetite. They mentioned giving her mirtazapine, but were a little hesitant because of her heart. I have not started the mirtazapine yet, because I wanted to research its use in dogs, and that is what led me to this site. I decided to leave this commentary after reading several people’s posts about their dogs. There are things out there that may help as you can see from my post. Two & 1/2 years ago, no one at the vet hospital recommended anything to me. There is no doubt in my mind, that my dog would not be here today if I hadn’t found the AllerG3 supplement, and the Wei Chi Booster. When I took her to the alternative vet, I told him about the dramatic improvement we had seen after giving her the AllerG3 for just one month, and he said that did not surprise him at all. I was really upset that if such a wonderful product exists and could possibly benefit my pet, why none of the doctors at the hospital would have recommended it or mentioned it to me. I was desperate and I would have done anything for my dog. Surgery and chemo are not always the best option for every dog, but I would encourage anyone to ask their vet about the AllerG3 or similar supplement and keep your minds open to alternative therapy, just do your research. If this post helps improve the life of just one dog (and owner), then I have achieved what I set out to do.

  2. Mom of Lance on September 13, 2011 at 7:34 pm

    To the kind attention of Dr. Dressler,

    It is with our greatest sadness that Lance (our 6 year old yellow labrador) was just diagnosed with Multiple Myeloma 2 days ago, Sept 10, 2011, we had him checked after noticing he didnt have the appetite to eat for nearly 2-3 days, and he has had decreased energy for 2 weeks which was unusual of Lance who is very active. They prescribed Mirtazapine 2 days ago, and today they have him on Prednisone for a week, before he starts Chemo…Is it safe to administer Mirtazapine and Prednisone at the same time?

    Thanking you in advance.
    Lance’s mom

    • DemianDressler on September 13, 2011 at 9:36 pm

      Dear Lance’s Mom,
      I am very sorry to hear about this. There is no direct interaction between these drugs known, and I have used them safely together. I hope you are also paying attention to the other steps in Full Spectrum Care- cancer diet, apoptogens, anti-metastatics, brain chemistry modification, and so on..Have you read the Guide?
      I hope this helps

  3. Nancy on August 18, 2011 at 8:52 am

    For those who want to try the natural ways for nausea, my vet give Ginger Mint 0.5 ml three times a day (my dog is 10 lbs) about 30 minutes before we gave them meal. It seems to help my dog. The brand I got is Animals’ Apawthecary. Good luck for all.

  4. Nancy on August 18, 2011 at 8:49 am

    For those who want to try the natural ways for nausea, my vet give Ginger Mint 0.5 ml three times a day (my dog is 10 lbs) about 30 minutes before we gave them meal. It seems to help my dog.

  5. Nancy Madden on June 17, 2011 at 8:19 am

    I have a 11.8 yr. old golden retriever (spayed) with lung cancer and possible metatisis. She is on Palladia but is losing her appetite. Is there any problem with giving her Mirtazaphine while she is on Palladia? I had some left over from when her father had cancer and I just want to make sure it won’t hurt her. She is also taking Benadryl 75 mg. twice a day, Derramaz 50 mg. once a day, and famotidine 20 twice a day. Would be so grateful for your opinion.
    Blessings, Nancy Madden

  6. Al Baker on September 8, 2010 at 4:23 pm


    Are you aware of any peer reviewed studies confirming the benefits of Remeron
    in treating nausea and appetite problems in dogs with cancer ?

    Thank You

  7. CIndy Richardson on July 12, 2010 at 12:00 pm

    I need some advise for my 3 yearold female boxer, was a very healthy active dog until about four weeks ago Zhoe’s neck became stiff she would not raise her head and when she would walk she would stumble. the vet first thought she had a bulging disk or a pinched nerve and was put on anti-inflammatory medication and pain pills. By the fourth day she was worse, her right leg became very weak and she would draw her paw up. We were referred to A&M for treatment and tests. MRI was preformed with contrast to see if there was damage or disease in the spine. GME, other forms of myetlities, or infiltrative neoplasia such as lymphoma. All tests have come came back in-conclusive. The vets are now saying in could be the onset of cancer or inflammatory disease. She has finished her antibotics and is to be started on a high dose of steriods. Is there not some test that show us if she has cancer? Also is there something from home that I can give (Supplements) to help combat her immune system. I can’t just sit back and watch her detoriate. this is very frustrating. I would appreciate any advise.

  8. celia on June 27, 2010 at 12:42 pm

    my 13 yrs old miniature dachshund has liver problems and her appetite was gone…started mirtazapine one week ago, 5 days 1 pill and then 1/2 pill. She’s responding very well, next week we’re going to cut down to 1/1 pill every 3 days. It’s great to see her eating again…

  9. Jamie W on April 10, 2010 at 8:36 pm

    My 9yo Mini Schnauzer developed a 2nd grade mast cell tumor last year. Our regular vet removed it, but due to it’s location (under her front leg joint) he sent us to a cancer specialist. She went through chemotherapy and it never bothered her. But after the chemo was done in November, they put her on Palladia. So with her being on predinizone and the palladia pills she was eating most of the time. They suggested doing a 5mg Pepcid AC each day plus we give her a Cerena pill on the days she takes the Palladia. She’s still been hesitant to eat at times and they put her on Mirtazapine. This has helped a lot I think. She has very few days where she refuses to eat now.

    • Dr. Dressler on April 12, 2010 at 12:09 am

      Dear Jamie,
      Thanks for your contribution, and glad your Mini Shnauzer is eating well again!
      Dr D

  10. […] (also called Remeron). Dr. Demian Dressler, author of the Dog Cancer Survival Guide, recently wrote about this drug. He says: “The medication is a very effective appetite stimulant.  This is particularly […]

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