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

Dog Cancer Surgery: They Didn’t Get It All Out

Updated: December 20th, 2019

Sound familiar? Did this happen to anyone out there?

Removal of all the cancer cells from the body during surgery is pretty important.  How can we tell?

The most important thing to do is get that biopsy report.  Some don’t want the extra cost.  “Just get it out” is a line I have heard from time to time. However, the report from the path lab can be absolutely critical.

Why does it matter?  Well, there are a couple of reasons.  First, the pathologist can evaluate the borders of the tissue I, or your vet/oncologist, submit after removal.  This is called comprehensive margin evaluation.

This evaluation tells us if there are cancer cells still left in the dog or not, around the surgery site anyway.  If there are cancer cells at the border of what gets turned in to the lab, there are probably some left in the dog.

So, if you get the path report back and there are cancer cells at the edge of the submitted specimen, it would be wise to go back in and remove more tissue. Yes, I am talking about a second surgery.

Some cancer types spread out around where the lump actually is resting.  So the dog will have cancer cells around the tumor that you can’t see with the naked eye. Some examples are osteosarcoma, some mast cell tumors, squamous cell carcinoma, fibrosarcoma, hemangiopericytoma (nerve sheath tumor), some mammary cancers (inflammatory carcinomas especially), hemangiosarcoma, malignant melanoma, and more.

In these cases, sometimes a wide excision (removing more than what “looks like” the cancer at the time of surgery is the way to go.  A fine needle aspirate or small biopsy before surgery can actually save cost in the end, by ascertaining whether a wide excision is needed before surgical removal.

Best to all,

Dr Dressler


Leave a Comment

  1. Mike Klorig on January 5, 2011 at 10:16 am

    Dr. Dressler-

    My 12 year old Bichon was diagnosed with a hermangiopericytoma on her chest. My vet operated on her and removed as much of the tumor as possible, but because of the location was sure that he was able to excise enough of the surrounding tissue to ensure complete removal. He stated that chemo is ineffective against these kinds of tumors and that because of the proximity to her heart that radiation was also not a viable option. He also stated that this type of tumor almost always returns if it isn’t completely excised. Before I found your website and purchased your book I started her on a homeopathic treatment plan of grain free dog food (EVO Red meat Formula), Essiac Tea, Immune System Supplements, and Flax Oil. Since purchasing your book I now have her on your cancer diet. Two questions: 1) Is there anything that I’m giving her that I shouldn’t and 2) Are tthere other treatment options that I can consider to prevent this tumor from returning?


    • DemianDressler on January 13, 2011 at 9:16 am

      Dear Mike,
      In the book we use a supplement plan that is different from what you are using.
      For example, look at this post (click here)
      Where is the big gun supplementation? Apocaps?? Why flax oil and not a higher concentration of EPA found in krill or fish oil? Are you paying attention to the brain chemistry?
      These are what caught my eye right off the bat.
      Dr D

  2. Patricia Lynch on December 31, 2010 at 5:34 pm

    My dog Mandi is a 4 1/2 year old part lab/rottie. 3 weeks ago we noticed that she has a lump on the rear outside part of her ankle. We took her to our vet who referred us to a surgeon. The surgeon is going to remove the lump but he does not know what it is until he cuts her open. What should we do if he cannot get all the margins? Should we get a second opinion. Thank you.

    • DemianDressler on January 13, 2011 at 9:11 am

      Dear Patricia,
      A fine needle aspirate should be done first to see if you can assess the cancer type and the need for a wide excision (the first time) if possible. This is discussed in detail in the Guide, which is an easy read and very useful in these types of decisions.
      Dr D

  3. Matt on March 9, 2010 at 3:18 am

    Dr. Dressler, thank you for your responce, it is on the knee area not the hock. It is loose and not attached, but it is at the front of the knee, the stitches will be similar to those on a torn ACL in a dog. Any thoughts on getting margins depth wise in this kind of location? In my experience with animals, there is no fat underneath this area, but more of a thick white membrane etc.

  4. Matt on March 4, 2010 at 9:09 am

    anyone have thoughts on this, when you take the skin of the leg area of an animal there is no fatty tissue to scrape, only the thick white membrane covering the knee and bone etc?

  5. Matt on March 3, 2010 at 4:25 am

    My almost 6 year old American Bulldog has a mast cell tumor, surgery set for a week or two from today. Tumor is size of a quarter on her rear knee, and loose not attached to leg. My concern is getting margins underneath the tumor, on the knee area there is no meat to scrape no depth to get?? Skin is pretty elastic there so margins in length should be ok (recovery will be a bear as that is not a still area) How deep can you go on a knee, or leg etc?

    • Dr. Dressler on March 8, 2010 at 3:58 pm

      Dear Matt,
      I wonder if you are talking about the knee, or the hock, which is a different joint? See the picture here. Anyway, really the concern is about maximizing the odds of a successful surgery. To really address this concern, I wonder whether you have considered getting a board-certified veterinary surgeon to help, or at least a second opinion? That way you know you are doing the very best thing for your dog. There are lots of other aspects to treatment you hopefully are considering too…
      Good luck,
      Dr D

  6. diane corbett on October 23, 2009 at 7:55 am

    it is me again my dog has just been confirmed with nasal carcioma. what suplements does he need right now

  7. Susan on March 1, 2009 at 7:16 pm

    Dr. Dressler,
    I have an 8 y/o Black Lab who is a 2 year MCT survivor. Started out with a pimple looking bump on her lip and ended up being a Grade 2 (borderline 3). The soft tissue surgeon cut a large wedge from her lip. She was then prescribed a regimen of 4 doses of Lomustine. It was after she started her chemo that more places started popping-up like crazy. The tumors did not slow until near the end of her last dose. She did not have any observed negative side-effects. We have continued with an ongoing dose of Prednisone (10 mg three times per week) and she has responded well to this dose. Still feeling well. This was a dog who was getting sick to her stomach multiple times per week prior to diagnosis, but she is healthy as can be and rarely ever sick now. Her energy level is dramtically improved as well!

    Shock for me came this month when my younger Chocolate Lab was also daignosed with MCT. She developed a little open sore on her chest. My vet aspirated and didn’t see any granulation. He recommended peroxide and neosporin. The spot did begin to dry up, scab, and appeared less inflamed. However, she eventually went back to messing with this same spot. The area was tested a second time and still no signs of granulation. However, my vet decided to remove it as it was obviously causing discomfort to my dog. He cut out the area under local anasthesia at the time of her vaccinations (lucky for me she takes large doses of Benadryl prior to vaccinations due to her negative reaction to the vaccinations). However, he was very shocked when it was reported by pathology as a MCT (grade 2). We went to see the oncologist that worked with my first Lab (three hours away). They did an ultrasound which was unremarkable, and they attempted to check her lymp node on the side of the tumor, but had difficulty manipulating her node as it was so small. The oncologist felt that all we needed to do was get better margins in light of the medical findings and the fact that she is not a repeat offender for MCT. So, my vet proceeded to go after better margins. Unfortunately, the second pathology still shows remnant cells at the incision site of the sample after securing better margins. My vet says that he doesn’t feel that he can take any more tissue without effecting locomotion as he has gone all the way down to the muscle sheath and the incision is about 6 inches in length with nearly 20 staples and sutures holding this together. The pathologist told my vet that he wouldn’t do anything further. I’m currently awaiting response from the pathologist.

    Based on your experience and expertise, do you think we should proceed with any other treatment? My baby acts like she feels just fine. She is alert, eating, and sleeping quite well. I don’t want to put her in undue pain, but I do want to be responsible and provide the appropriate care.

    I asked the oncologist (during our visit) about using supplements and she told me we could certainly try some supplements if we would like, but she did not want to supervise or make any recommendations as she feels there is not enough scientific evidence or FDA control to make such recommendations. My lab is 73 lbs. and I am open to any suggestions you might make.

    Thank you in advance for taking the time to read this, and thank you so much for all the helpful information and kind responses you are giving to folks such as myself.

    • Dr. Dressler on March 7, 2009 at 4:33 pm

      Susan, I cannot make individual recommendations for specific dogs. However, various supplements can be used, including luteolin, apigenin, curcumin, cordyceps/beta glucans, omega 3 fatty acids, artemisinin, and others. There is a full spectrum plan that might help in the e-book, The Dog Cancer Survival Guide. You can also find blog posts on these.

  8. patricia1594 on February 27, 2009 at 12:23 am

    My 11 1/2 yr old cocker had a 13 pound tumor chondrasarcoma removed two months ago. During the surgery which was a last ditch effort to save her life, her heart arrested three time. She was revived by heart massage and epi injections. The incision made by the vet was as big a he could do but the tumor was so big (the size of a deflated basketball) that he had to close her up. She was in ICU for 3 days and received 2 blood transfusions. Within a few weeks it was obvious that part of the tumor was still there. Six weeks after her original surgery, when her blood stats were good enough, she had a second surgery to remove a tumor the size of a large golf ball. Within 2 days she was bouncing around the house like nothing had happened. Both tumors were on her abdominal wall and during the second surgery he reoved as much of a margin without doing damage to her diaphram. He also biopsied spots on her liver which came back no cancer. She will likely be on wholistic cancer meds for sometime just in case. A picture of my dog with the tumor laying next to her can be seen at Thank you for this wonderful and informative website.

  9. Dr. Demian Dressler on October 27, 2008 at 11:41 am

    See my comment from your other post…

  10. deann on October 25, 2008 at 7:50 pm


    I have pennypie, and I saw Dr. Dressler, in the begining of
    her lymphoma. Now it has been 1 1/2 years, and she is still
    alive. I was giving her, Q10, Vit e, C. and good food. I was
    told low, but good natural protien, was good. Also, I guess
    the standard treatment was pred. She had a bad incident,
    a couple of weeks ago, and I thought we would loose her. However, I was told to double the dose, of pred, and it brought her back, ufortunately, she has become paralized in her back legs, but she is happy and eating well, except for her paralysis. She is incontinent, mostly with urine. She can wag her tail, and she knows something is wrong, but I don’t know what to do from here. They say she was not supposed to last
    this long, and I know it was the antioxidants, at least in part, what I don’t know is what to do from here.
    Deann Colton
    I had very little money to have extensive testing done.
    I also gave her salmon oil, and vit d3, and some tabs from
    shitake mushrooms.
    thanks, and aloha from Kihei, Deann

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