More melatonin and dog cancer - Dog Cancer Blog

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

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More melatonin and dog cancer

Ya want more on melatonin? You just hit the jackpot!

Why should we be interested in this stuff?  First of all, melatonin used with chemo versus chemo alone more than doubled the survival time of human cancer patients. Big effect here folks.  Secondly, melatonin decreased the side effects related to chemotherapy.  These included low platelet counts, irritations of the lining of the mouth (stomatitis), nervous system injury (neurotoxicity), and heart toxicity (cardiotoxicity).  Here is the abstract.

Now, don’t go away mad, because there is more.  Melatonin helps overcome weight loss due to cancer (cancer cachexia)  in advanced cancer patients, with no change in how much food they are eating. As if this were not enough, a study looked at over 600 cancer patients with a variety of solid-tissue tumors received melatonin.  The 1 year survival time of the group that took melatonin was more than a third greater than those that did not.

Melatonin was the topic of a medical conference which discussed the ability of melatonin to cause some cancer cells to not only die off directly, but go back to being healthy body cells, and decrease cancer spread (metastasis). To boot, melatonin is an immune stimulator.

Anyway, lots of promising stuff here.  One of the points made at the NIH conference mentioned was that this information has been around for years, but for some mysterious reason has not made it into the medical or veterinary knowledge pool.  As I pointed out in the last post, I think the obvious reason is that you can’t patent it, which means no pharmaceutical company marketing for sales…but we’ll go over that in some future post.

Anyway, here’s the skinny on side effects and whatnot…  Don’t give your dog melatonin during the daytime, it messes up the circadian rhythm and causes headaches.  Any supplement given by mouth has potential for digestive upset (vomiting or nausea).  If your dog has any immune mediated disease (like some types of underactive thryoid problems, dry eye, lupus, pemphigus, allergies, and so on), avoid it. Don’t give it to your dog if he or she is on calcium channel blockers (some types of heart and blood pressure meds), or is on fluoxetine (Prozac).  Diabetic dogs may need less insulin on melatonin. If your dog has diabetes, begin melatonin only with your vet’s close supervision and instruction, otherwise skip melatonin. If your dog is an epileptic, I would avoid melatonin as well.

There are statements suggesting melatonin should not be used with leukemia or lymphoma patients circulating around.  I have tried to find some actual evidence for these (a paper, case report, anything real) but to no avail.  Any input from the readers? Same thing with this idea that it can cause retinal injury- appears to be speculation, but I am open to any documented, real evidence.

Doses vary.  For early dog cancer patients, use about 1-2 mg per 40 lbs body weight, once a day, given at night.  For advanced dog cancer patients, use about 5 mg per 40 lbs.  Give with food.

There are ways to help increase your dog’s natural melatonin levels that don’t cost a cent.  Make sure your loved dog sleeps in total darkness, 10 hours daily.  No TV glare, no computer monitor, no nighlight.  If you are doing home cooking, give melatonin-rich food.  The highest is brown rice and oats, but carbs are not good calorie sources for dogs with cancer.  Try some fresh sage, lots of naturally occurring melatonin in sage leaf. Keep your dog away from high voltage, as electric fields cause melatonin levels to drop. Meditate with your dog.  My friend Jim Jacobson wrote a book on it.  Meditation increases melatonin levels.

Best to all,

Dr Dressler




About the Author: Demian Dressler, DVM

Dr. Demian Dressler, DVM is known as the "dog cancer vet" and is author of The Dog Cancer Survival Guide: Full Spectrum Treatments to Optimize Your Dog's Life Quality and Longevity.

  • My dog Candy was prescribed a melatonin regimen for her Atypical Cushings– meaning that her hormones were out of whack but she had normal cortisol (steroid) levels on the Tennessee Adrenal Panel. But, melatonin is also prescribed as an alternative treatment for dogs with Cushings who do have high cortisol (steroid) levels. I was giving melatonin and phosphatidylserine (to keep cortisol levels in check)
    Some are using melatonin patches in lieu of oral melatonin to deliver a supposed more reliable, even dose and some claim that it prevents daytime drowsiness. So, I guess what I am saying is that when dogs have high steroid levels (cortisol) that melatonin is being touted as in Cushings disease (high cortisol levels) to prevent panting, excessive thirst, excessive urination etc….. So does melatonin lower cortisol level or modulate it? In your case would the melatonin modulate or lower the pred, thereby canceling out the pred or have no effect. I guess Dr. Dressler will help us out here.

    Would prednisolone have fewer side effects than prednisone–I heard that on one of my lists. Also there is a compounded version of prednisone without the negative effects of prednisone but the same benefits. Best of both worlds–same positive effect, none of the negative effects. Some have used this form to reduce liver enzymes. I don’t know if this is anecdotal information or supported by studies.

    I have taken Candy off melatonin now because of some things I have read to not give it with a lymphoproliferative cancer, as in cutaneous T cell lympoma which Candy has–also called Mycosis Fungoides. I understand it has promise with organ tumors though.

    I don’t know for a fact about the interference of Pred with Melatonin but thought this info would help provide some understanding of the mechanism of action for which it is used in Cushings.


  • oops, error above, I meant melatonin implants, (in lieu of oral melatonin) not patches.


  • Dr. Dressler

    1. There is not an interaction between pred and melatonin. There was a study using dexamethasone where melatonin blocked the suppression of normal immune responses (but not the suppression of cancerous white blood cells).
    2. The effects of melatonin in cushing’s is mediated by sex hormone imbalance and effects of it on hair follicles and other body systems, not by suppression of cortisol or the other corticosteroids that are in excess in typical cushings.

    Melatek markets Dermatonin, the implants. They have a web site:

    Check it out for further reading.
    Dr D

  • Patrick B

    Hi Dr. Drexler:

    You wrote, “There are statements suggesting melatonin should not be used with leukemia or lymphoma patients circulating around.”

    I have read that melatonin also has antioxidant properties. That may be the reason for the statements. I have found that many vets, as I am sure you are aware, tell their clients to never give any antioxidants when receiving chemotherapy.

    Do you have some current thoughts on this subject?


  • Eve

    Where did you come up with this info?
    My vet and the vets at the University of Tenn, all have put my dog on this.
    Check out Dr Oliver at the vet university of Tenn.
    He knows more about atypical cushing’s then most.
    So tell us where you got this info, what medical test have you done to prove this?

  • Karen Bender

    Hi Doc – my Mack is an 11 yr golden with meningioma of olfactory lobe. He is on prednisone 10mg every other day and phenobarb 75mg bid. Can he take melatonin for sleep? After sleeping quite well at night since he was diag’d in Sept’08 has recently been up at night panting. His wt is 84-85lbs. How much can he take? Thank you so much in advance,
    Karen Bender

  • karen bender

    Hi Doc – I understand melatonin can be taken in addition to prednisone, but what about along with PHENOBARB?

    Thank you so much,

    • Dr. Dressler

      Karen, I do not see a immediate conflict aside from excessive sedation possibly. There have been no studies though, so the use of these together has not been shown to be definitively safe. In the realm of neurotransmitter modification, nobody knows the whole real story…just not enough info yet..

  • Karen Bender

    Thank you, Dr.Dressle, for your response. Mack is getting closer to the end now. I stopped the melatonin (only gave it to him for about 5 nights) and he actually slept better last night. I lowered his prednisone (initially he was on 10mg every other day until our vet raised him to 10mb bid last week.) Maybe that was keeping him up, also. He is still eating heartily, still wags his tail when I come home, and still barks at people passing the house. He is having labored breathing somewhat. I just don’t know where the fine line lies between his feeling well and actually starting to die. I don’t want it to be an emergency euthanasia, but I don’t want to do it prematuely either.
    Thank you for helping and listening,

  • jean brickwedde

    I have a 13yr old spayed female Akita, diagnosed with Cushings, not yet determined if adrenal or pituitary, and has hypothyroidism, and have just started her on Ridlin for her weakening ( and I assmue painful ) hind quarter.
    Can melatonin help relieve the symptoms of Cushings, regardless of which type, and if not, why not?; and what does the hypothyroid have to do with it?
    I appreciate your answer.
    Thank you
    Jean Brickwedde

  • jean brickwedde

    Sorry, Rimadyl, not Ridilin

  • Kristen

    Dr. Dressler,

    Why do you say avoid melatonin if your dog is epileptic? A lot of canine epilepsy sites recommend it.

    Thank you,

  • Jane DeBlasio

    I have a question for Dr. Dressler
    My dog was diagnosed with atypical cushings (pituitary tumor/sex hormone elevation)
    I was told to give 3 mg. of melatonin in the morning and 3 mg. of melatonin at night along with flax. I read your article about the problem with giving melatonin in the daytime. I also spoke with Dr. Oliver from Tennessee who told me that this has been the regimen for atypical cushings for the past 10 years. What is the best way to administer melatonin to my dog? Also, will giving melatonin in the daytime cause health risks for my dog?

    Thank you.

  • lyn

    Beg to differ with the doc but according to Dr Oliver “STEROID PROFILES IN THE DIAGNOSIS OF CANINE ADRENAL DISORDERS” under sub heading melatonin “Also, in dogs with adrenal disease that are treated with melatonin, and repeat adrenal steroid panels are done, cortisol levels are consistently reduced, and estradiol levels are variably reduced.29 Inhibition of the 21-hydroxylase enzyme would lower cortisol levels, and inhibition of the aromatase enzyme would lower estradiol levels. Estradiol levels were decreased in a prior study of dogs treated with melatonin.31 Results of in vitro studies with human MCF-7 breast cancer cells also revealed that melatonin inhibited aromatase enzyme, which resulted in reduced estradiol levels.56 Melatonin treatment for cases of mild adrenal disease in dogs may be effective, and particularly in cases where sex steroids are increased.”

  • Laurie

    Hannah, my beautiful 50 lb.,14 year old Siberian Husky has inoperable cancer probably originating on an adrenal gland and atypical Cushing’s. At this point in time, her quality of life is not too bad. An ultrasound suggests the cancer has spread; an X-ray shows a very enlarged liver, blood work shows some very elevated liver enzymes. I am trying to reconcile melatonin dosage recommendations: Cushing’s protocol says 3 mg twice a day; cancer protocol suggests 6 mg. evenings; then I see internet references to melatonin being contraindicated for dogs with liver disease because melatonin is hard on the liver. Help! Hannah has been taking melatonin one month; and I can see its positive effects on her overall well being and functioning, including fur growth; though that is the least of my concerns. What would you do with a dog with a confluence of issues like this? At this point in time she is taking lignans, milk thistle, melatonin, PS, DGB, Wei Qi, a multiple vitamin and may add Stasis Breaker later. Weaned off Metacam and Tramadol; recently had an Adequan series of injections. Trying to give her liver as much of a break as possible; but very aware of melatonin’s cancer fighting properties, not to mention the Cushing’s. She is eating high protein grainless commercial canned and kibble ; laced with chicken breast; although I did give home-cooked a real try. Too many peas and carrots now, I know, but it is the compromise she and I arrived at. For the first time, last night I switched to 6mg melatonin in the evening, but I am worried about it. Should I continue to give her as much as 6 mg, once a day with her stressed liver? Should I give her less? Her vet is as conflicted as I am. What do you think? Thank you so much.