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

Help Metastasis with Flax Lignans

Updated: May 15th, 2024

In the world of Full Spectrum care for dog cancer, we try to look for anything that gives us an edge.  This edge could be related to survival, life quality, decreasing treatment side effects, or finding something that just works better than the old way.

This is a major goal of The Dog Cancer Survival Guide, as well as the development Apocaps, that I use in my patients.

Since new information is always emerging, new strategies can be used and applied for dogs with cancer.  An interesting option, especially for dogs with melanoma or mammary cancer,  is the use of flax.

Flax has been around for millenia and used for a variety of things.  These days it is garnering major attention for it’s possible benefit in women with certain kinds of breast cancer.

Why the excitement?

There is some real evidence, at least in lab animals with experimental tumors, that large amounts of flax in the diet have real-life effects in real-life bodies.

For example,   it has been shown that mice with malignant melanoma had less metastasis when given flax.  This means that the melanoma cells spread into the body less often.  In another study in mice with certain kinds of breast cancer, the addition of flax slowed the spread of the cancer by metastasis.  When mice with breast cancers had them removed with surgery, the rate of cancer spread after the surgery went down when the mice were supplemented with flax.

How does it work? Here are a few of the most well documented ways.  The most interesting thing that flax may do is help cancer cells decide to commit suicide.  This process is called apoptosis.  The components in Apocaps do this very potently, so it is neat that flax has a little of this effect as a side feature.

Flax contains a fair amount of omega-3 fatty acids, which have benefit for cancer patients.  There are also compounds called lignans in flax, which seem to exert many of the anticancer effects.

Finally it seems that flax lignans are able to decrease the accumulation of zinc in cancer cells, studies show.  Cancer cells seem to need these high zinc levels to function, and it may be that by blocking  cancer cells’  zinc uptake,  flax exerts an effect.

There are several different flax lignans, but the one with the highest amounts has been shown to be secoisolariciresinol.  I can’t pronounce it either.

We should all keep certain things in mind.  One consideration is that the studies were in mice with implanted cancers and not dogs.  Another is that very large amounts of flax were given to these mice, 10% of their diet.  If you imagine a dog eating a diet that is 10% flax by weight, it might not even be edible.

Nonetheless, flax is safe, palatable, and can be mixed in a home-made or canned ration pretty easily.  I would imagine three or four times the human dose for a large breed dog would be a decent guess at dosing, but please consult with your veterinarian or oncologist before changing anything in your dog’s health care plan.


Dr D

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  1. Susan Kazara Harper on May 1, 2014 at 4:36 am

    Hi Jane, no, you’ve violated no rules, and we welcome opinions and experiences. We also know how panicked a person can get when their dog is diagnosed with cancer. I surely experienced panic and the desire to find everything that would help when two of my dogs were diagnosed within a year of each other. So I know many people who have given their dog anything and everything that they believe can help, and sometimes it all just doesn’t work together and the dog feels pretty rough trying to digest it all. It’s possible to find anything online and many of those things make claims of success. They may well have success, yet we do always want to see that there is solid evidence behind a particular substance working, beyond testimonial. So we’re always going to advise on caution and working with one’s vet. Whether or not the vet believes in and agrees with what the guardian wants to do, if they don’t know everything that is being given, they cannot help avoid contraindications or conflicts. So truly, thank you for your contribution. All the best!

  2. Susan Kazara Harper on May 1, 2014 at 3:00 am

    Thank you, Jane,
    This is interesting information.
    We recommend all treatments, including complementary and supplemental substances be coordinated with your veterinarian, and advise that only practitioners qualified in the treatment of animals prescribe or use substances such as homeopathy including tinctures, and other remedies.

    Any substance which can make a difference can also create a conflict or upset, so caution is advised.
    Interactions with other prescription and non-prescription substances may occur. Please coordinate everything with your veterinarian.
    Please also remember that some substances are toxic to dogs at certain levels, and others are toxic altogether. And dosing for humans is often much lower than for dogs, because dogs have a shorter intestinal tract than we do. It’s not a simple matter of weight equals dose for all species.

    Without being an expert in pharmacology or toxicology, it’s a bad idea to figure out dosing all on your own. While the drive to help our beautiful dogs is so strong, sometimes more is just too much. Be careful, friends, and all the best!

    • jane hand on May 1, 2014 at 3:32 am

      This is not info by me but by a doctor who cured incurable diseases with a 90% success rate for decades,

      He worked on many many animals from small to horses etc. Nearly everyone who came to him the last 10 plus years of his practice had been given up by doctors and told to go home and die many were supposed to be dead months ago..they were terminal..the rest were people with incurable diseases like blindness, ms, myastenia gravis etc. so he is very experienced in dealing with cancer and with cancer in animals. ‘

      I trust what he says. On one of the stories he tells of a vet who said horse was dead and he got better with herbs even though then Dr Schulze was not very experienced and gave the horse too much but it did save the horse’s life even thought he vet said he would kill the horse that the vet said had zero chance to live when owner knowing how good Dr Schulze was insisted that he try to help her beloved horse.

      The dosing is very accurate. Here is his post on it.

      A good site for healing animals naturally is Shirley’s wellness cafe.

      I am sorry if my posting this info violated some rule on here..I am not familiar with the site but saw some people interested in dosing and i thought they would benefit from this info.

      Often with both people and animals natural healing can cure something doctors cannot and at far less price. There are millions of people who cured incurable diseases and cancer many against all odds because they were brave enough or desperate enough to try.

      i am not so sure how many vets would give things like tinctures as this is not how the average vet is trained. Might they not be like doctors advising against all alternative treatments saying they are quackery or useless. When a doctor says there is no cure what they really mean is there is no cure I know of, was taught or believe in not that there is no cure.

      Natural healing is more organic to living beings and in most cases far far safer.

      i hope you will let my post and difference of opinion or viewpoint stand. I have studied alternative health for over 35 years quite intensely and in fact, am using it not doctors other than a non recommended lumpectomy over mastectomy) to hopefully try to cure my aggressive cancer that was recently diagnosed.

      So I believe strongly in study on our own and the benefits of natural healing and in fact have helped others heal successfully…stopping heat attacks, helping people reverse stage 5 kidney disease to normal shocking the person’s doctor etc.

      What i have learned and testimonies I have read have helped me to be able to trust my instincts

      Now that my life is on the line, it is very scary and I might fail but so might the treatments of doctor and if they do cure at what cost to health and quality of life…and it does take bravery to set out on a diiferent path then most chose in regards to cancer.

      If I listened only to doctors and not my gut and research, I might be cured, I might no, t but I know the risk is very serious and that chemo etc can cause permanent brain damage/brain shrinkage. severe memory loss, drop on IQ and cognitive functioning, permanent damage to the liver, lungs, heart, immune system, lymph system etc.

      It is not wrong to try to help ourselves and animals with all the knowledge out there…doctors are not really trained in disease cure but rather disease management except in trauma situations like a car wreck.

  3. jane hand on April 26, 2014 at 1:45 am

    Use clark’s rule of dosing for kiids or pets or very obese people is based on weight.

    Let’s say we ae using a tincture. The normal tincture dose for a peson weighing 150 pounds is 60 drops.

    we take the p[et or kid’s weight and put it over on the top of the fraction bar with 150 at the bottom. Let’s say a cat weighs 10 lbs.

    take 10/150 and reduce it to 1/15th so a cat would in this example take 1/15th of the dose of 60 or 4 drops

    Let’s say a dog weighs 50 lbs the take 50/150 and reduce it to 1/3 so 1/3rd of 60 drops is 20 drops so a 50 lb dog would in this example take 20 drops

    Let’s say a preteen weighs 75 lbs that would be 75/150 = 1/2 so that kid would take 30 drops. a 300 lb man would do 300/150 = 2 so he would take twice the dose of 60 drops or 120 drops/

    Clark’s rule can be applied to tea, powders even capsules by emptying them an measuring the adult dose then taking 1/10th of it or whatever the animal or person’s weight is

  4. Megan on October 19, 2010 at 9:38 am

    Dear Dr. D,

    Have there been any studies done with metformin? Recently, it has been suggested that meftormin (a human medication to treat type II diabetes) has the ability to greatly slow tumor growth in humans. It was especially helpful in slowing breast tumor growth. I am very familiar with human medications, as I am a Doctor of Pharmacy, but I was wondering if you have heard of any success or even a promising clinical study relating this to our canine companions. My interest in this mainly comes from my love for my little rescue dog, Swiffer. Swiffer is an intact female JRT/doxie mix, who is also diabetic. She also has breast tumors, which I believe are cancerous. We rescued Swiffer in February, 2010, and she was in such bad shape that no vet wanted to put her under anesthesia to biopsy the tumors. When we rescued Swiffer, she was severely emaciated, has uncontrolled diabetes, and several infections…as well as being blind. She has since made an amazing recovery from her initial state, however her heat cycle still wreaks havoc with her blood glucose levels–to the point of preventing Swiffer from having her potentially cancerous lumps investigated.
    Please let me know if you have heard anything regarding the use of metformin in dogs to slow cancer growth.
    Thank you for having such a wonderful and informative website!

  5. Dr. Dressler on April 21, 2010 at 10:17 am

    Thank you for your input and helpful hints!
    Dr D

  6. Philip Caldwell on April 21, 2010 at 7:29 am

    Dr. D,

    It is nice to see you referencing mice studies and anything that gives relief to our small animals without side-effects. Last month, when I suggested resveratrol for dogs for a cancer preventive and therapeutic treatment you were looking for studies specific to dogs.

    You specifically called dog owners off resveratrol who might have benefited from resveratrol supplementation in spite of the fact that there is glaring evidence from numerous animal studies showing resveratrol to be a potent anti-cancer agent in animal studies.

    I do agree that flax and many other natural products should be incorporated in a dog’s diet and not only for cancer afflicted dogs but as a preventive for most dogs.

    In fact, the resveratrol supplement for dogs that I had mentioned in a previous posting (which will go un-named here lest I be accused of endorsing a product on your site) does in, fact, contain flaxseed oil together with resveratrol.

    You had a question about bioavailability (absorption) in dogs thinking the dog’s digestive system might render the resveratrol inert before entering the bloodstream. It is actualy well absorbed. You asked to see evidence of this and here is the National Institute of Health article regarding this specific to small animals including dogs.

    In any event, you are to be congratulated for this posting aimed toward a more natural protocol.



    • Dr. Dressler on May 3, 2010 at 1:33 am

      Dear Phillip
      The blood concentrations in the rats in the paragraph you referenced were found to be 2.5 micrograms per liter. The apoptosis inducting effects of resveratrol in vitro are found at 25-50 micrograms per liter on average. The reason the blood concentrations are low due to the conjugation of resveratrol, mainly through gluconuridation by primarily the liver but to some extent by brush border enzymes as it is absorbed. So the systemic levels of the flavonoid are low, which is agreed upon by researchers in this area at this time.
      As I have stated previously, although resveratrol is very interesting, we need a good way to get the substance up to 10-20 fold blood concentrations since it does not seem to accumulate in tumor tissue.
      I do feel it has a lot of potential, it is just that there are things that need to be worked on. Injectable resveratrol is a nice idea..also oral resveratrol may have some nice applications for tumors lining the upper GI tract where it can contact the tumor cells directly, or by creating an analogue (previously discussed in the blog). Safety studies in dogs would be nice you have access to those?
      If it is shown safe in dogs, then little harm in considering with other supplements as long as there are no interfering effects with other treatments in a given patient..
      Thanks for your thoughts

  7. Kevin Coombs on April 19, 2010 at 1:22 pm

    Another is that very large amounts of flax were given to these mice, 10% of their diet. If you imagine a dog eating a diet that is 10% flax by weight, it might not even be edible.

    Nonetheless, flax is safe, palatable, and can be mixed in a home-made or canned ration pretty easily. I would imagine three or four times the human dose for a large breed dog would be a decent guess at dosing, but please consult with your veterinarian or oncologist before changing anything in your dog’s health care plan.


    Our dog has prostate cancer, fairly advanced. We are currently using a flaxseed oil & cottage cheese mix (the Budwig diet) to prevent cancer growth in our dog. It is not very palatable, so we mix a small amount of Virgin Coconut Oil in to sweeten it .. then mix that into his specially cooked meal .. the meal is based on your book, which we bought last month. The mix seems to go down OK most days.

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