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

The oncologist’s thoughts on what to do after the aspirate confirms mast cell tumor?

Updated: October 10th, 2018

In my recent blog, we discussed the aspirate that confirmed the diagnosis of mast cell tumor (MCT.)

Now there is a decision to make, should you have your dog staged to make sure the MCT has not spread, or should you proceed to surgery to remove the tumor and find out the grade?

Remember what I said in this MCT post, this is not a one-size-fits-all tumor, meaning there is not a checklist or single protocol for all dogs. MCT is a complicated cancer.

Some Guardians choose to stage the cancer without knowing the grade, because if it has spread they might not go through with surgery and may just do chemotherapy, or no therapy. Other Guardians want to remove the tumor, get the grade information, and then proceed with staging tests.

Why go to surgery?

If I have a dog with his first MCT and there is only one MCT, going to surgery is typically the next step. If possible, the goal of surgery is to remove the entire visible tumor along with a wide (usually 2 to 3 cm on all sides and a layer of tissue below) margin of surrounding normal tissue. The surgical margin must be confirmed clean with the pathologist’s report. The surgical biopsy also provides the grade. Grade is one of the most important prognostic (or predictive) factors for MCT. We will discuss that in the next blog.

Location location location!

Who should do surgery? If the tumor is large or in a region where getting clean margins will be challenging, I urge you to consider seeing a board-certified surgeon. A good example is a MCT on a leg – there’s just not a lot of tissue on these areas, especially the further down the leg towards the paw.

There is evidence that board-certified surgeons are more aggressive in their approach – in a good way; they typically remove more tissue, which results in cleaner margins and fewer cancer recurrences.

Wide excision — which means a big incision or cut — is the best way to achieve local tumor control (prevent cancer from recurring).  Surgeons actually measure around the tumor and mark the measurements on the skin before making incisions at surgery.

If the margins are not clean, I am likely to recommend a 2nd “scar revision” surgery. Which means the surgeon will have to go back and “revise” the scar — make it wider, basically, to get the tumor out completely. This is one reason I urge you to see a board-certified surgeon first, because your dog may require fewer surgeries. The first surgery is the best time to remove the entire tumor.

What if more than one MCT?

If there is more than one tumor, it is recommended to biopsy each one, because each separate tumor could be of a different grade and need a different course of treatment. If there are many tumors – more than four or five – I will often biopsy the two largest or the ones which have grown most quickly, depending upon the specific case, the location and size of the tumors, and my own discernment.

Do I stage prior to surgery and knowing grade? What does staging include?

It is always reasonable to look for spread prior to surgery. However, if your dog has a single Grade I tumor, further staging before surgery is probably not necessary.

But in all other cases – two or more tumors of any grade, a Grade II or III tumor, a recurrent MCT tumor, or lymph node metastasis – further staging is necessary before deciding upon a course of treatment.

If you did surgery 1st and the biopsy reported a Grade II or III MCT, I will recommend staging after surgery.

Staging should include at a minimum an aspirate of lymph nodes in the region of the tumor or tumors (even if they are of normal size) and an abdominal ultrasound to check for internal metastasis. A bone marrow aspirate may also be needed.

Why an abdominal ultrasound? In addition to spreading to the draining lymph nodes, MCT tends to spread to the liver, spleen, and sometimes internal lymph nodes; an abdominal ultrasound will reveal suspicious lesions or enlarged, infiltrated organs. If these are found, it does not necessarily mean that there is metastasis; the organs should be aspirated to confirm the situation. In most dogs, aspirates are done using ultrasound-guidance and can be done without sedation.

There is still some controversy about whether normal liver and spleen should be aspirated. But a recent study (Stefanello 2009), showed that normal-appearing organs can still be infiltrated with MCT, and dogs with aspirates that confirmed this sadly lived much shorter. So it is important to know that if the liver and spleen are normal on the ultrasound, this may be a false negative. While the procedure is safe, quick, and harmless in most cases, it is important to go through the pros and cons with your oncologist.

Next blog will be about the biopsy report, grade, and mitotic index. In the meantime, remember there is a lot more information on MCT, including staging tests, in the Guide.

Leave a Comment

  1. Elma Martin on August 12, 2016 at 2:13 am

    Hi Susan, I am very grateful to have found your blog. Thank you for sharing your thoughts. Wish you lots of happiness. Elma XXX

  2. Charlie W. on December 7, 2012 at 2:46 pm

    My precious dog Dude, 12 yrs old was diagnosed with oral Fibrosarcoma during dental procedure. I was devistated and when to an oncologist, he was administered chemo (dox) & peroxicam and got extremely ill 8 days after, so was referred to another oncologist who suggested palliative radiation (6 rounds) which shrunk the tumor, but then it was wait and see. I started doing my own in depth research and contacted surgeons (oncologist & local surgeon said too late for surgery and to make him as comfortable as possible for the next 6 to 12 months). I found in my research that chemo is not effective on oral fibrosarcomas, and surgery followed by radiation is best. But, decided to travel 2 hours to the nearest University with a vet/oncology program. I am so glad I did. They were optimist about Dudes condition, are willing to do surgery and had a plan for him as far as medicine that works best with this type of tumor, they also agreed chemo is not effective for this tumor so I wasted around $800. for one chemo treatment. I should have pursued surgery immediately. Anyway, they are on the cutting edge of canine cancer treatments where the oncologists seem to be stuck in their ways not on top of the newest medications and treatment. The university doctors were immediately attentive to Dude and explained everything clearly even educating me on a white board with drawings and statistics. They said after surgery he will be on Palladia and another medication. These cut off blood supply to cancer cells, which causes them to grow and another medication that inhibits cell division I believe. Anyway, I now have hope instead of crying every day. Dude is also being supported by a raw diet and immune support, Flaxseed and fish oil. I guess what I’m saying is check with your nearest university vet program, it may save your precious companion! All my best to you and your furry family member, and my deepest sadness for your loss.

    • Dr. Susan Ettinger on December 29, 2012 at 6:08 pm

      Thanks for sharing your story with Dude. Your story highlights the importance of getting a 2nd opinion, whether at a university or another referral center. Wishing you and Dude continued success!
      All my best, Dr Sue

  3. Linda on October 13, 2012 at 4:38 pm

    My white boxer Jessie who is an angel was brought to the vets for a cough and she spit up a little blood once. We left the office after the xray with Vet sadly telling me she has a big tumor pressing on her lung. My son and I are so upset. I did some research on an over the counter drug when I googled how to shrink tumors in boxers or dogs. They said get benadryl 25 ml and tagamet 200mg give twice a day if there is a tumor and once a day to prevent one. The xrays the woman showed the tumor shrunk in three months. I gave it to her last night and her breathing in one day was so bad. She is 9 and they do not recomend surgury. I dont know what to do. They didnt give me prednisone or pain meds and said to try to enjoy the next few weeks and were sincere. During the day she still wants to walk to the beach, eat, play and then at night is tired and breathing heavy. She is like a daughter to me as my son is 21 in his last yr in college. I think during a physical especially for a boxer an xray should be suggested. I may have had time to catch this. When I went in for her last physical I asked the doctor if they fealt any lumps and that I was worried she could get cancer. Im not a vet—instead the vet said it was just fatty tissue. I know my finances are low but why would they say lets do an xray on her since she is 8???? It should be required and if the customer wants to decline oh well, however I wouldnt have. To quick of a visit that does cost money but leaving without all the facts. A simple xray. I shouldnt have known that after loosing my parents at 60. Please pray for Jessie, I have a copy of her xrays if anyone knows how to read them to tell me what they think. Im now missing work and staying home with her ans I am self employed. Please pray for my Jessie the best dog I have ever had and loves everyone!!! Linda in Marshfield Ma

  4. debra on September 27, 2012 at 3:41 am

    Good morning. I felt the need to post this in the hopes of many things. My Max is a beautiful chow mix. Max has had two MCT removal surgeries. The first was devastating, the stitches covering most of the lenght of his back and a lot of his side. Stage 3, good clean margins. Came home with drainage tubes. He took it in stride, bless him; nothing kept him down. That was October 2010. Seven months later another MCT , Stage 3, was found and removed in May. Since the second surgery Max has been on an herbal supplement in the hopes of keeping the tumors away, and of course a grain free diet, along with additional immune boosting supplements. Well, last month we found two more MCT. During researching, I came across a posting from a man I wish I could thank in person, it may even have been on this site somewhere. He spoke about a drug called Vetalog and his experience with it over a long period of time. LONG – that was what attracted me. Max is ten now, will be eleven in February. I was considering a new chemo therapy medicine in pill form which I understand is having great results but it frightened me. So I contacted my vet about Vetalog, who said it was “old school.” We decided to give it a try. The side effects are drinking a lot of water and urinating. I could not care less about that stuff, which by the way, Max had one, yes one accident. Two weeks after the first shots, we got the best possible results. My vet says when we go back in another two weeks (which is a week from today) he does not believe he will be able to even find one of the tumors. No, we are no where near out of the woods. But to me. as a non-medical person, Max’s skin looked almost normal. The one tumor is almost gone, the other great improvement. Almost flat. Now I don’t know if there will be long term benefits from this; quite honestly I don’t even know if there will be any significant short term benefits as it has only been three weeks, but Vetalog is an option. Many of you may know about this – I didn’t – so I wanted to share. Also, as many of us know surgery is expensive, costing several thousand dollars. Not everyone can afford to do this for their pets so this may be an alternate treatment, even if for a short time. It is an INEXPENSIVE treatment and so far in this very short period of time, for us, is working. I cannot say what the long term affects are, but I am hopful and grateful for every day with Max and hope God grants us much more time together. I hope this helps someone out there. I will update on the status, and if anyone has bad news about this drug, please break it to me gently. God bless you all in your struggle with this terrible cancer.

    • Dr. Susan Ettinger on September 30, 2012 at 5:11 pm

      Hi Debra,
      Vetalog is a steroid, a different form of prednisone. It is well- known that steroids can have an anti-cancer effect against mast cell tumors. Typically, the cancer will develop resistance and the anti-cancer effect is not durable. But in some cases, like your Max, it can help for longer periods, which is great for Max. 🙂
      As you mentioned, side effects include increased drinking, eating and urination. And steroids do suppress the immune system and can lead to infections as a result. They can also lead to diabetes, so it’s important to see a vet regularly.
      I am glad the steroid in working for Max, and thanks for sharing. There is more about steroids and mast cell tumors in the chapter in the Guide.
      I wish you continued success with Max’s treatment.
      All my best, Dr sue

  5. Sarah on August 31, 2012 at 1:19 am

    My 8 year old pitty has had reoccuring grade 1 MCT which has all been removed with surgery, all clean margins. Each time he was put on pred for a month. This has happened multiple times over the past 2 years and every time a tumor shows up the day one is removed through surgery. He is also on benedryl, tagamet, CAS options and low fat grain free food. He gets a runny nose sometimes but other than that acts happy and healthy as can be. Not sure what to do!! Thoughts? Thanks!

    • Dr. Susan Ettinger on September 7, 2012 at 11:52 am

      Hi Sarah.
      Some dogs unfortunately are what I call repeat offenders with MCT. It is good to keep removing them and make sure the tumor is submitted to the lab for grading and margins EACH time, because it is possible that new MCT can be different grades. The use of chemotherapy for dogs with multiple MCT is controversial, meaning whether it will prevent new ones is debatable. But it can be considered. When not on pred, you can add Apocaps and check out the Guide for other supplement suggestions.
      All my best, Dr Sue

  6. Vivian on August 21, 2012 at 7:49 pm

    Thanks for the post! My Boston Terrier wast determined to have MCT and had a surgery few months ago to completely remove. Though I’ve read the grading part in the book, I’m still looking very forward to see if more information could be given. The report came back, just stating the grades and the staging. I’m still very worried. Now we are following the eating diets accordingly, however as most food is made in China, not sure if it would be better than eating dry dog food.

    Heard that Budwig Diet’s pretty good on humans, not sure about dogs… As one of the key ingredient in the Dog Cancer book is organic Cottage Cheese. Any suggestions on your viewpoints toward flaxseed oil?

  7. Jeannette Botza on August 21, 2012 at 1:38 pm

    Can you please give some information on Hemangiosarcoma. My dog was
    diagnosed with a mass in the right atrium, but the oncologist said it did not have
    the appearance of hemangio, but we did 4 sessisions of chemo and after 2nd
    session the massin the atrium was no longer visible after being checked by the
    cardiologist. After the 4th session ultrasound did not see any mass in liver, spleen, or anywhere else. I did not do metronomic thereapy as she did no handle it well. Oncololgist said if I didn’t do, cancer would return and it would
    be to late, and I wold lose her. Nevertheless I staged her every month for 5
    months and nothing was seen, on the 6th month it was in her liver and spleen,
    I am totally devestated, is this return becuase I did not do metronomic therapy:
    I am so riddled with guilt, that am now in thereapy. Please reply

  8. Kuma and Joann on August 21, 2012 at 8:25 am

    My precious chow mix Kuma was just euthanized this August 9th at 6:30 pm he had his oral tumor debulked twice but could not get clean margins. He still got the melanoma vaccines but tumor came back a third time. He did make it 8 months but soon his breathing became labored and he started to show signs of struggling. I am deeply upset for my loss:(
    Kuma and Joann

  9. Erica on August 21, 2012 at 3:26 am


    My 7 year old lab was just diagnosed with anal sac adnocarcinoma. It has also spread to the iliac lymph node as well as 1 other. My husband and I are going back and forth- surgery, surgery and chemo, or just nothing and spoil him rotten for the next few weeks, months, etc. I think we have agreed to AT LEAST do surgery and maybe look into holistic medicine as an approach.

    • Dr. Susan Ettinger on August 27, 2012 at 4:03 pm

      Hi Erica,
      Sorry you hear about your lab. Surgery is the most important treatment option of surgery, radiation, and chemo, if you only pick one. With that said, combined treatments often lead to better prognosis. There is a chapter on anal sac adenocarcinomas in the Guide if you are looking for more info. And meet with an oncologist if you can. Good luck! I know it is not easy.
      All my best, Dr Sue

  10. Ben on August 18, 2012 at 5:57 pm

    Thanks for the post. I’m looking forward to the next one: my labrador’s path report just came back as grade II, 0 out of 10 mitotic index. The margins were clean but not very wide. The tumor was also both cutaneous and subcutaneous, with the bottom margin only 0.2 cm. I have the guide, and I’m learning about the diet and leaning towards implementation with a low-to-none histamine content.

    I think I’ll also consult with a local oncologist about further options. Thanks again.

    • Dr. Susan Ettinger on August 27, 2012 at 3:48 pm

      Sounds great. Working on the next post, things have been hectic here in my clinic. But stay tuned, and thanks for reading!
      All my best, Dr Sue

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