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

Magnesium and Dog Cancer

Updated: May 15th, 2024

The strategy of Full Spectrum Care is used in the Dog Cancer Survival Guide to take advantage of anything that is safe and effective to get an edge on dog cancer.

This means we have to look not only at chemo, radiation and surgery, but also on all those other things that might help a loved dog live a better, longer life.

One of the biggies in nutrition.

This area has perhaps gotten a lot less attention than it deserves.  We can remove a rusted car door, but if the engines is out of gas, or if we should be giving diesel instead, we get nowhere.

Magnesium is  like the forgotten fuel in the car with a rusted out door.  We see the door and everyone pays a lot of attention to the hole in the door. But we forget about magnesium.

Why does it matter?

Magnesium is extremely important in the body.  Hundreds of normal body reactions need magnesium. Not only is it critical for a healthy immune system, it also plays a central role in production and use of the body’s energy molecule, ATP.

Less ATP, less fuel to fight cancer.

Here’s the juicy part. It turns out that cancer lowers magnesium levels in the body.

In a study of critically ill human cancer patients, it was shown that almost half of them had low magnesium levels.  We know that the process of cancer itself seems to cause depletion of magnesium in the body.

On top of this, studies show the chemotherapy drug cisplatin is more prone to causing kidney damage with  low magnesium levels.  Cisplatin is used in common chemo treatments,  most frequently  for dogs with osteosarcoma.

A strange twist in the magnesium story is that excessive magnesium in the body can increase the odds of cancer development.  For this reason, we want to be careful not to over supplement with magnesium.

In the dog cancer diet recipe found in The Guide, you will find that certain grains are included.  Now, generally speaking, cancer diets should be fairly low in most kinds of carbs.  However, this is not a black and white story. Carb restriction is different from carb elimination.

Whole grains like steel cut oats and brown rice contain good levels of magnesium.  Lignans and beta glucans found in these grains are also known cancer-fighters.

For this reason, I recommend a portion of these grains in a good dog cancer diet.

It is for the same reason that I included a bit of magnesium in the supplement designed for use with my patients (Apocaps).

Let us not forget to keep good fuel in the tanks of our loved dogs.


Dr D

Leave a Comment

  1. Angie Theodorakis on June 18, 2015 at 11:06 am

    I just read your message about Heartgard Plus…do you still have your dog? The reason I am saying this is that I would steer clear from this stuff…terrible for cats and dogs..

  2. Marcela on May 27, 2010 at 4:52 pm

    Our lab, 13 years and a half, had surgery 2 months ago due to bone cancer in his rear leg. I’m preparing his food according to recipe,his is doing very good, but I would like to know your brand recommendations for bone meal, oyster shell calcium and krill oil.
    There are too many brands, and many of them contain other ingredients that I don’t know if can be useful, or worst, harmful.


    • Dr. Dressler on June 6, 2010 at 11:05 pm

      Hi Marcela,
      I have been advocating staying away from bone meal with osteosarcoma (I don’t know if this is what your dog has or not):
      Most of the large name brand human supplements are safe for krill oil and oyster shell calcium.
      Dr Dressler

  3. Shirley & Lucille on May 16, 2010 at 1:50 pm

    Dear Dr. Dressler,
    Thank you so very much for your suggestions. I do have Heartgard Plus currently and that should also take care of any intestinal parasites she may encounter or should I look into trying to find plain Heartgard? Is it still availible? Also I will only use maybe a permrithrin dip made for puppies on her then, with her thick coat I don’t think a spray would penatrate enough to get to her skin and if I’m going to use something on her I want it to have a chance of being effective but I will only use the dip just before we leave so that I will hopefully not have to use it more than the one time.
    Thank you again for your time and suggestions as I do feel more comfortable about taking this trip. Best Regards, Shirley and Lucille, our wonder-pup

    • Dr. Dressler on May 22, 2010 at 5:21 pm

      Dear Shirly and Lucille,
      I feel that Heartgard Plus should be okay.
      Dr D

  4. Shirley & Lucille on May 15, 2010 at 9:16 am

    Dear Dr. Dressler,
    I have been a follower of your articles and Blog since late in 2008 and I can say that I have always found your information to be very helpful too. A subject that I have not seen listed in the newsletters or seen in the Blog either, but I could have missed though, is on how to protect our furkids, those who are now fighting cancer, is how to prevent them from getting things like Heartworm, intestinal parasites, fleas, ticks and if they should get any of these, how do we safely, this being the optium word, treat them? It is now seventeen months since our Golden girl was diagnosed with Mast Cell Cancer, Gr 2, Stage II mit. index of 5. Surgery was done to remove the mass and then three months of Chemotherapy followed. She has been on a homemade most of her life but to that has been added Springtime’s Longveity, Krill Oil, your ApoCaps and Dog-Immune by K9Medicinals. She is doing well and enjoying life and every day is a blessing to have her still with us. This Summer we will be taking a trip into a area where she could possible come into contact with fleas, ticks and also Heartworm so our concern is how do we protect her from these parasites? Since she was diagnosed in late 2008 I have not used any type preventative on her nor have I had her vaccinated. I do vaccine titers and all her levels are strong so I have no worries there only with the flea, tick, intestinal parasite and Heartworms issues do I have questions. Do you have any recommendations on what can be used or what do you suggest to your clients to use as I know that your area has problems there with Heartworm and fleas too. Thank you ahead of time for your time and reply to my questions.

    • Dr. Dressler on May 16, 2010 at 10:33 am

      Dear Shirley and Lucille,
      Great question. Generally we have to weigh pros and cons. If one looks at the data, the pesticides have some carcinogenic potential. That being said, topical permrithrin products for fleas are probably the least harmful of the bunch. The heartworm products seem generally ok.
      Dr D

  5. Malanie on May 8, 2010 at 6:28 pm

    My heart goes out to you. I can’t imagine how hard this is for you. My golden is 7 and we are battling his mast cell tumor with everything we’ve got. I can’t imagine loosing him. So sorry you are grieving.

  6. Mike on May 6, 2010 at 6:45 pm


    I am so sorry for your loss. My dog has been fighting lymphoma for over a year, and just yesterday I found out the current chemo is no longer working. Everyday we have our beloved companions, with us, is a treasure. I try to prepare myself for what is coming, but I know, until that day, I truly don’t know how you are feeling. I wish you all the best.
    Regards, Mike

  7. Cat on May 6, 2010 at 7:23 am

    My dog just passed away from cancer. I am grateful to all of the information you provided throughout his illness, but it is too hard to open my e-mail and see “dog cancer” all the time. I would like to be taken off the subscription list as I no longer need the information. Keep up the good work. Thank You, Cat

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