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

An Antibiotic for Dog Cancer

Updated: March 20th, 2019

Antibiotics are normally used to treat infections, but not many know that there are anti-tumor antibiotics.

One of the cheapest, safest, and most easily obtained through a vet? Doxycycline.  Now, doxycycline is not a dream antibiotic.  It actually has fairly limited use as an antibiotic.  Some use it for dental infections, but it is most commonly used to treat certain blood parasites.

Some exciting news about doxy?  It has anticancer effects!

Doxycyline helps suppress angiogenesis (new blood vessel formation that feeds tumors and robs the body). In this way it slows tumor growth. It blocks enzymes called matrix metalloproteinases (MMP’s) that digest the tissue around tumors, allowing new blood vessels to be formed. Check it out here.

Not having access to as much blood supply, the cancer cells are less able to metastasize through the circulation.  This lessens the spread of some cancers. Read more.

In the lab, this drug can induce apoptosis (normal, healthy, programmed death) of cancer cells.  This is a direct action on the cancer cells, and may have some usefulness in cancers like lymphosarcoma. Here’s the abstract.

In humans, this drug has been a disappointment for cancer treatment.  But in dogs, according to Greg Oglivie, MMP inhibitors (of which doxy is one) combined with chemo for lymphosarcoma improved survival times in some older dogs in double blind, placebo-controlled clinical trials.

Although this is a prescription drug, it is widely available and inexpensive.  It can be used with most other agents used in fighting cancer, and is quite safe.

When young dogs take doxycycline, some may develop yellowed teeth. It may cause abnormalities in the cartilage of developing pups in the uterus, so do not give it to pregnant dogs.  It should not be given with calcium-containing foods as this may lessen absorption of the drug.

Best to all,

Dr D

Discover the Full Spectrum Approach to Dog Cancer

Leave a Comment

  1. Justine Freeman on March 20, 2019 at 3:21 am

    Can Doxy be used in conjunction with Apocaps?

  2. Ann Shonert on March 13, 2019 at 5:36 am

    I have a Boston Terrier with 3 or 4 cancerous lesions…diagnosed by aspiration by a vet in August. I was told he’d have maybe 3 months to live. They gave me 5mg Prednisone & I myself started him on a half benedryl daily.
    3 months later read about doxy. G began giving him a dose daily. I know it’s not good to self treat. But, the vet refused to do anything else. This is a well know full surgical vet hospital in MO. Putter…the Boston is doing fine. Lessions have grown a little. I’m scared to death of losing him. I just don’t know if my dosage is exact & for how long I should use doxy,??

    • Dog Cancer Vet Team on March 13, 2019 at 6:30 am

      Hi Ann,

      Thanks for writing, and we’re sorry to hear about your boy. 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. D’s writings 🙂

      On pages 192-193 of the Dog Cancer Survival Guide, Dr. D provides more information on doxycycline including the precautions and dosage 🙂

  3. Lisa kalis on February 5, 2019 at 9:02 am

    Can a dog with diabetes AND cancer take the antibiotic doxycycline my rottie is 9 on supplements wondering if this will do any good?

    • Molly Jacobson on February 5, 2019 at 9:58 am

      Hi Lisa, check with your veterinarian about whether doxycycline will affect your pup’s diabetes. I’m not sure whether it affects blood sugar levels, but your vet will be able to find out. Plus, you need to get the med from your veterinarian anyway — so ask when you bring this up in your next visit. Thanks!

  4. Our Baby on April 3, 2014 at 2:33 pm

    The Vet says our 15 yr old Cocker has a malignant tumor in her mouth on her gum. Recommended surgery, chemo and radiation. We said NO. We started her on our own protocol of “DCA, Turmeric and Baking Soda” once daily wrapped up in her favorite deli ham. The tumor has shrunk by 1/2 in 3 weeks!! We are ecstatic!! Her over all health signs are improving as well.

    • kimber's mom on May 10, 2014 at 9:38 pm

      What is DCA?

  5. Ann on March 2, 2013 at 5:10 pm

    Our beautful girl, Ollie, a 10 year old golden retriever, has been diagnosed with cancer.

    Early fall 2012- She starts vomitting right after eating. Vet suggest 2 pepcid in with food. Vomitting stops.
    Mid Nov. 2012- We first notice a “lump” in her neck.
    Dec. 31, 2013-We take go to the vet. Needle asperation. Vet says it’s probably lymphoma. We wait for results.
    4 days later- Vet calls can’t believe it’s not lymphoma. Maybe tick borne disease. Starts doxycycline 2 pills twice a day. We give it to her. she vomits. We space out the pills and give them every 3 hours. 8am, 11am, 5pm, 8pm
    2 weeks later we return to the vet. No change in glands. He explains we aren’t giving the dose right. We get 2 more weeks of pills and give them correctly. 2 at 8am, 2 at 6pm. After about 10 day lymphnodes shrink alittle.
    Then grow back bigger.
    return to the vet more glands now involved shoulder and groin area.
    We go to specialist, oncologist, Recommendation Have a gland completely removed, tested in California.
    Feb-19 She has surgery and is prescribed antibiotics.
    Feb. 26 results/diagnosis-low grade small cell lymphoma t-zone type.
    Feb. 28-We go back for node measurement becuase she is acting sluggish.
    The vet examines her groin area and notices an area of concern that she (nor the other 4 vets) had not felt before. She asperates it.
    She sees (a couple irregular cells). She nows has Ollie has either Histiocytic sarcoma, Hemangiosarcoma, or Soft Tissue sarcoma. The next step would be more surgery, test, x-rays, mri’s. etc. In the end the area is in a place that would likely require amputating her rear leg. (We aren’t doing that)
    We gave the last antibiotic pill yesterday.
    Today, the huge glands in neck neck are either gone or have shrunk 75%.

    So my question is should we start doxycyline. My though being the restriction of blood supply to these areas.

    Thank you

    • Dr. Demian Dressler on March 6, 2013 at 4:16 pm

      Dear Ann
      I am sorry you and your dog are going through this. Goldens are now the number one dog that get dog cancer, with about 75% of them getting the disease. So your dog may indeed have two cancer types. As to whether we have tick borne blood parasitism, there are tests for that which should be done to rule them in or out. Discuss starting doxy again with your vet as it may have caused vomiting…you could give it with a full meal and also use some mirtazapine or metoclopramide along with it to help with nausea. Again, touch base with your vet. Have you read the Guide so you are aware of all the options you have?
      I hope this helps
      Dr D

  6. Mark on January 4, 2013 at 7:44 pm

    Hi Doctor Dressler..
    My 11yr old boxercross had a phantom pregnancy, lactating etc 3mths ago…then had a little lump form in one of her rear glands..BBsize,
    The vet prescribed cephalexan 500mg and after only 7 days the lump grew to the size of a golfball which then was diagnosed as a malignant tumor,
    (It does make me wonder whether certain meds feed the tumor or fight them..?)
    She had surgery,3 of the chain removered and seemed to recover well..
    Unfortunately..a month later the tumor returned and another formed on the other rear remaining breast.
    Her lymph nodes under her arms are swollen and she has fluid building up on her underbelly/chest and rear legs have swollen.
    Today i visited the surgeon and he prescribed Prednisone 20mg..thinking surgery just delaying the inevitable..
    Any suggestions how to prelong her life as shes still very active would be much appreciated..?
    (also would the navy protocol help in anyway?)

    • Dr. Demian Dressler on January 29, 2013 at 5:52 pm

      Dear Mark,
      was your dog spayed? This can help decrease some cases of mammary cancer regrowth. Also I would be thinking of the other steps in the Guide- diet, apoptogens, immune support, and so on. The chemo options are a bit limited with most mammary cancers I am sorry to say.
      Maybe this will help:
      Dr D

  7. Vadym on June 19, 2012 at 7:23 am

    Dr. Dressler:
    We have a dachshund, 13 years.
    2.5 years ago she had a surgery and mammary glands 4 and 5 were removed from each side.
    Biopsy showed a cancer. She was ok until this February when it came back.
    It looks horrible, whole belly is like pomegranate and it is bleeding and spreading.
    She always was on protein diet , only raw meat.
    Now she is taking meat , spinach, garlic, broccoli and fish oil, echinacea, propolis.
    Would Doxycycline be helpfull for her to slow down the process?
    Thank you.

  8. mike on June 14, 2012 at 3:38 pm

    Hello doc,

    I recently got the bad news that my 11 year old german shepard had an anal sac tumor. We had the tumor taken out last week, she is recovering fairly quickly. Our vet just called yesterday to tell us the tumor test results came pretty much as expected-anal sac andeocarcinoma. We can’t afford chemo nor do I want to put her through any more stressful vet trips….any prescription/natural meds you can recommend would be greatly appreciated. Baytril? Pre-surgery I would have never even known she had any problems what so ever. Extremely playful and never stops running and enjoying life! Post surgery she almost can sense I know this is very threatening.

    Thanks for any response.

  9. Roland on May 9, 2012 at 4:06 pm

    Hi Dr D my 9 year old collie X has been diagnosed with osteocarcinoma in the skull. I have decided against surgery and Chemo as cost is prohibitive and benefits are uncertain. He is now on a cancer diet and I have ordered Artemix. I am wondering if Doxy and Artemix could be combined?

  10. Austine on February 7, 2012 at 6:12 am

    10.5 y/o Labrador/terrier has Mct. Can the doxycycline help her?

  11. Julius Moultrie III on December 20, 2011 at 7:51 am

    Dr. Dressler:

    My 4.5 year old French Mastiff was diagnosed 1 week ago with canine lymphoma with a tumor in his chest, abodomen, and 2 under his mouth. Currently we are give him 2 Prednisone pills a day, 1morning/1evening. He has a great appetite and loves the his high calorie meals with 1tbls of flax seed oil that he gets. We are waiting for the K9 Immunity Plus with Transfer factor to be delivered so we can include it with his present treatment. Should we also start giving him Apocaps as well?

    • Dr. Demian Dressler on December 21, 2011 at 8:42 am

      Dear Julius,
      I assume conventional chemo has been thoroughly evaluated? This is one of the most treatable cancers with chemo.
      If you are relying on Prednisolone only, the life extension is usually only a couple of months.
      Apocaps with pred can be done, but needs to be monitored very closely by your vet. I worry about digestive upset (vomiting, diarhea, loss of appeitite) if the pred dose is high (can’t tell based on comments) or if your pooch has a sensitive stomach.
      Talk with your vet about using Apocaps on days off pred or at 1/4 the labeled dose with food.
      Flax oil is has much less beneficial effect than krill or fish oil, as you will read in the Guide, which I always recommend.

  12. Angie Jones on November 9, 2010 at 4:57 pm

    Dr. Dressler,
    My beagle, Gordon, is just coming out of remission of his lymphoma. He started a rescue protocol (Madison-Wisconsin) yesterday. I asked our vet if he was familiar with LDN which he wasn’t but he is familiar with the doxycycline studies.

    He is supportive of our interest in trying it but not sure what the dosage is for our 42 pound beagle. Can you help?


  13. vapor cannon on June 30, 2009 at 4:04 am

    its nice to know that Doxycycline can be used to fight cancer to human and even in dogs. Thank you for sharing this article.

  14. Edith on March 29, 2009 at 5:43 pm

    Dr. Dressler, do you know anything about noscopine? My 14 y/o labradoodle is 2 ys 2 mos post lymphoma diagnosis. He had a NC State multi-agent chemo protocol in 2007, went into remission within a month. Came out 12-07 and went on single agent doxorubicin. Almost immediately went into remission which held until 11-08 when he developed 4 lumps in various places on the right side of his body. Tried procarbazine for 3 cycles. After the 1st, the lumps went away, but shortly after the 3rd began, a new lump developed. Switched back to doxorubicin. Lump went away in less than a week, but I’m scared of the doxo. Read about noscopine, but cannot get human researcher or the company they are working with to return calls/email. My vet oncologist wanted me to find out about any canine safety studies which may give us dosage info. Do you have info about this European OTC cough medicine ingredient? Thanks.

  15. John on March 29, 2009 at 3:13 pm

    You apparently have not read the latest research on antiangiogenic drugs, they do not suppress blood vessel formation, just the opposite! Use of these drugs actually enhances the integrity of tumor blood vessels, and can promote faster tumor growth.


  16. Joanne on March 8, 2009 at 8:21 am

    Dear Dr. D.,
    Benny has Mast Cell Tumours and he has had the cortisone injection (the one you recommended and I cannot remember the name….intra…tra..)and the tumour did not shrink much. Today it bled a little and my husband administered the powder form inside a Yunnan Baiyao capsule to the tumour. We also gave him a the other half of the capsule in some liverwurst. What are your opinions on this particular supplement being used in dogs with MCTs? We are willing to try anything to insure that his quality of life remains as good as it is right now. He eats well and enjoys his daily CANINE LIFE muffin and is very happy on walks.


    • Dr. Dressler on March 9, 2009 at 4:16 pm

      sometimes we look at a lack of growth as success!!
      Now, I am not a Chinese Medicine expert by any means, but I believe Yuannan Baiyao is more suited to other tumor types…another thing that some have used is topical quercetin (powder on the tumor). I have not but it is an option. Discuss with your vet as usual!


  17. Val on February 14, 2009 at 5:07 pm

    Dear Dr.
    I have started our 5 year old golden mountain dog on Dichloroacete (DCA). He has lymphoma and was diagnosed Jan 14. He is on prednisone, 8 – 10 mg of DCA, B100, magnisum 100 mg. 500mg of evening primrose and baytril. I am wondering if doxycycline is a better choice of antibiotics. He is doing much better now that he is on DCA and I hope that this note will help other people with cancer in their dogs to go to the DCA site and see what miracles are happening with its use, even if it is only in trials… you can still order it from buydca.com.
    Good luck eveyone with your pets.

  18. Gail Casey on January 22, 2009 at 8:20 am

    Dr. Dressler,
    My mixed rescue 12 year old pup was diagnosed with nasal adenocarcinoma in Aug. 2006. After consultation with a well respected radiologist/oncologist here in the LA area, he underwent surgery and radiation (newer protocol due to improved equipment). His tumor has reacurred but Metacam, fish oil, Agaricus mushroom caps, Yunnan Paiyao, Glucosomine and immune support along with a partial raw diet (he can’t handle total protein) have kept it growing slowly. He still loves his walks and seems happy. Recently his sneezing increased and occasionally he again has a small bit of bloody discharge. Is doxycycline recommended for this type of cancer? I realize I have had him far longer than is usual for this type of cancer and for that I am grateful but would still like to do whatever I can to keep his quality of life good. Any other supplements you can suggest?
    Thank you.

    • Dr. Dressler on January 30, 2009 at 8:17 pm

      Gail, this (like many questions I get here) has a very long answer, which is why the e-book is coming. Short answer though:
      Doxycycline is definitely a thought, especially with the epistaxis (nasal bleeding). The studies were not done with nasal ACA but that does not mean it is not a good option. Discuss with your oncologist. I would consider it for sure.
      Best of luck,

  19. Karen on January 19, 2009 at 5:54 pm

    Dear Dr.Dressler,
    My 10 1/2 yr golden was diagnosed 9/4/08 with a brain tumor/hemangioma, preempted by 3 grande mal seizures on 8/30/08. His prognosis was 3-6 months. On 2/4/09 it will be 5 mos. We are not doing chemo, radiation, or chemo, but we are do phenobarb and prednisone. He is still a happy boy, walking 1-2 miles per day and still (thank God) seizure-free. We are also doing Vit C, Fish Oil, Astragulus, Pignogenol, Green Tea, CoQ10, Milk Thistle, and Sam-e, along with Tissue Tone, and Chlor-oxygen and glucosomine for his arthritis. Any other recommendations?
    Thank you so much for your sharing of your knowledge and your wonderful attitude!
    Karen Bender
    Springfield, NJ

    • Dr. Dressler on January 30, 2009 at 8:26 pm

      Karen, I am sorry to hear this yucky news. Hm. You might want to consider methyl jasmonate. I’ve never used in personally in dogs but check it out with your vet/oncologist. It is inhaled from a steam-type vaporizer. Hard to do maybe, but depends on your dog. Check out Stephen Martin’s blog Grouppe Kurosawa for some stuff on this. Also definitely look into Lutimax and discuss with your vet/oncologist.
      Good luck,

  20. Michelle on January 19, 2009 at 8:27 am

    My dog had mast cell tumors stage I and is currently on Leukeran. Is this antibotic something that I should consider giving her with her chemo treatment?

    Thanks, Michelle

    • Dr. Dressler on January 19, 2009 at 3:18 pm

      Hi Michelle, you might want to check with your oncologist about the white count. If the count is low, I would certainly consider it, after discussing with your vet or oncologist. My e-book will be answering these questions in a lot of detail.
      Good luck

  21. Shavonne Harpole on January 19, 2009 at 8:13 am

    Dear Dr. Dressler,
    My four year old english bulldog was diagnosed with lymphoma in July. She started the 5 drug chemotherapy protocol for 19 weeks. She went into remission after the first treatment and appears to still be in remission. Is the doxycline something I should add to her treatment when the cancer comes back or currently while she is still in remission? My dog means everything to me and I would do anything for her. Please give me your opinion. I really respect your work in dog cancer and wish there were more of you.

    • Dr. Dressler on January 19, 2009 at 3:14 pm

      Hi Shavonne,
      I would perhaps consider some of the other supplements discussed here, making sure you have consulted with your vet or oncologist. Perhaps EGCG, Curcumin, fish oil,ginger would be some considerations. You might want to look into my upcoming e-book too, the dog cancer survival guide,which will be available for downloading within 2-3 weeks, which answers questions like this and presents a full spectrum plan (diet, supplements, and more). It is the first of it’s kind, so I am pretty excited about it! Thanks for the compliment by the way!

  22. Donna Becker on January 19, 2009 at 3:51 am

    I am sorry you didnt get to say good bye for him..that must have broke your heart into a million pieces…

  23. candice on January 8, 2009 at 7:40 am

    my boyfriends mom took his dog to the vet because we noticed he had a lump or 2 under his chin and they gave him antibotics and said give them to him until they are gone and wait and see if lumps go down-about a week or 2 later we come home and she put the dog to sleep, we didn’t even get to say goodbye-we didn’t even know she was going to do it. They said he had cancer of the lyphnoids. He did not seem at all like he was in pain and I have yet to find out how long he had it or when it had developed. Why would the vet be ok with putting the beloved dog down? his mom has alot of issues, but why do it if the dog didn’t seem like it was suffering.

    • Dr. Dressler on January 15, 2009 at 12:26 am

      perhaps they wanted to make sure they prevented suffering that was going to happen in the future, so they made sure there was never any negative life quality from the cancer. This is my only explanation, but it could make sense.
      Hang in there,

      • Jill on May 23, 2011 at 12:55 pm

        My 9 year old lab has been diagnosed with lymphoma. He mostly has good days wanting to play ball and go for walks at a slower pace then usual but still active.
        He is currently on a 5 day treatment(round two) of cyclophosph and prednizone daily. He’s eating like a champ(I cook a high protein/high healthy fat diet for him).
        white cell count came down from 42,000 to 5,400 but his glands are swelling again. would this doxycycline help him? We’ve been treating him for about 4 weeks now.

        • DemianDressler on May 25, 2011 at 8:56 pm

          Dear Jill,
          I am a bit worried about your lab. I would be reaching for more than doxycycline if his glands are getting larger. The chemo should be adjusted by your vet or oncologist. Also, there are a lot of other steps that you could be taking. I assume you are using apoptogens, omega-3 fatty acids, immune support, and the other steps in the Guide??
          I hope this helps

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