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

How Long to “Watch and Wait”

Updated: December 6th, 2019

Last week I told you about two recent cases in which the tumors were too big for surgery by the time they came to me. I also promised to give you some guidelines about how long to wait when your vet says “let’s just monitor this.” Too many lumps and bumps are being monitored for too long … so this post contains some guidelines.

The Vaccine-Associated Feline Sarcoma Task Force of the American Veterinary Medical Association has guidelines based on their work looking at sarcomas occurring at vaccination sites. While these guidelines were created for cats originally, and the first rule refers to vaccine injection sites, in my experience these guidelines apply to dogs, as well.

According to this “1-2-3 Rule,” you should get a lump or bump aspirated right away if any of the following is true for your dog:

  1. The mass is increasing in size one month after injection.
  2. The mass is greater than two centimeters in diameter.
  3. The mass persists for longer than three months

So, if your dog’s lump or bump is increasing in size after a month, bigger than two centimeters (just under an inch), or hasn’t gone away after three months – get it checked!

 Phew: It’s Benign.

Hopefully, the mass will turn out to be benign. If that’s true, it may not need to be removed right away.

A lot depends upon where a benign tumor is located. If it’s causing pain, it might be keeping your dog uncomfortable. On the other hand, if removing it would be a complicated surgery – it’s near a joint, or it is on the lower limb where there just isn’t much tissue to work with – it might not be worth removing.

If it does need to be removed, most benign masses require smaller surgeries. We don’t worry as much about getting wide margins. Also, sometimes the surgery can be combined with another procedure that requires anesthesia. For example, if your dog is getting his teeth cleaned and undergoing anesthesia for that, your vet might offer to remove the benign tumor at the same time. The risks of anesthesia are real, too, after all.

Oh, no. It’s malignant.

If the aspirate comes back indicating the mass is malignant, remember that it is often better to get a small surgical biopsy to determine the type of malignant tumor and the grade before going for a curative surgery.  I may also recommend staging diagnostics first, before the curative surgery. This is a complicated subject, I’ve written about in several posts, including this one on mast cell tumors.

 Surgery Might Be All You Need

Surgery is often all we need to treat many cancers, so please, do not wait too long to get a lump or bump checked out. Remember Tiger and Tulip? Both could have had great prognoses, if the tumors were removed with clean margins the first time, when the tumor was small enough to get out. Now, surgery would harm more than help, and they are stuck with radiation, which is less effective for measurable sarcomas, or chemotherapy, which is much less effective for primary tumors than it is for metastasis.

As your dog’s guardian, make sure you read biopsy reports. Tiger’s mom was unaware of the dirty margins that were reported on the biopsy from his first surgery a year ago. If she’d known then about the incomplete margins, and that it meant his tumor was more likely to recur, she would have had more time to address the situation.

What About Recurrence?

That said, even with a clean margin reported on the biopsy, tumors can still regrow from microscopic cancer cells we don’t see in the biopsy. So we must all monitor for regrowth. Some tumors, like Tiger’s, are in a location that you can see. Others, like those inside the mouth or inside body cavities, you might need to check with imaging tests or sedated exams.

If your dog’s tumor is malignant and you have it removed, recheck it every two to three months after the surgery. Early detection of recurrence is key to addressing it with the highest possible chances of success.

The Bottom Line

Please, don’t watch and wait as a mass grows, because there is a point at which it will be too big to address. Have your vet measure and document the size of the tumor, so you can compare growth. Aspirate or biopsy that mass, if needed. And make sure you find out about the margins after surgery. Were they wide enough for that tumor type? If not find out if there can be a scar revision (second surgery), or if radiation can prevent regrowth, or chemotherapy can slow recurrence. Be proactive. Check with an oncologist, and please, don’t monitor for too long.

Remember the “1-2-3” Rule and get that lump or bump aspirated right away if any of the following is true for your dog:

  1. The mass is increasing in size one month after injection.
  2. The mass is greater than two centimeters in diameter.
  3. The mass persists for longer than three months

All the Best,

Dr. Sue

Leave a Comment

  1. Holly on January 21, 2013 at 12:01 pm

    My 10 year old Australian Shepard was diagnosed with anal sac adenocarcinoma in both anal sacs on July 2, 2012. After surgery to remove both anal glands and a lymph node (metasticized) he received 6 treatments of chemotherapy. His recheck on November 15, 2012 showed no evidence of cancer. On December 26, 2012 blood tests and x-rays showed that the cancer had returned. His calcium levels were scary high and there was sign of another tumor growth in his tummy. I love my dog so much, but decided not to put him through another surgery only to have the cancer return so quickly. Did I make the right decision? His Oncologist has him on another 6 chemo treatments, along with palladia given at home. In less than a month we have spent over $2,000 (total over $13,000) and I am still not sure the outcome to expect from this new treatment. I was so disappointed that the cancer returned 6 months later when I was told one year or more. I just don’t know what to believe anymore and if I am doing the right thing for me and my boy.

  2. Ron Sholar on January 4, 2013 at 10:29 pm

    I design and built veterinary hospitals throughout the U.S., which does not make us experts as veterinarians. i know that vets. kind of look at danes as cash flow for them, because they are so large and grow quickly that they have many issues.
    Thank you for for your thoughts…

  3. Ron Sholar on January 4, 2013 at 10:23 pm

    i had a three year old great dane that died of lymphomas at the jaw line on both sides. The breeder was from Missouri and i believe a puppy farm.
    Our current danes are from a well know long time breeder from the Chicago area. The younger of the great danes is 3 1/2 years and has a small lump (1/2 inch) on the right side of the jaw line. I am nervous about it because of of the past (i guess you will say have it checked). The other dane is 6 years old and she is fine except she has a few bump on the top of the neck and on top of the rib cage. i have thought this is because of them playing hard. (same breeder but not the same blood line).

    • Dr. Susan Ettinger on January 13, 2013 at 4:58 pm

      Hi Ron,
      Sorry about your Dane with lymphoma. Never easy to lose a pet!
      You are correct, I recommend you go get the mass checked out – probably start with an aspirate. See what your vet says.
      All my best, Dr Sue

  4. Deb on December 31, 2012 at 11:58 pm

    As I can’t get Tagamet or Pepcid otc in Australia can I subtitute Zantac? My girl weighs 25kg so what is a safe dose?

    • Dr. Demian Dressler on January 2, 2013 at 12:23 pm

      Deb, you need to discuss this with your veterinarian to see whether there are any problems giving Zantac to your dog. But Zantac has been used in the dog to decrease stomach acid, yes. Discuss with your vet please…
      Dr D

  5. BARBARA on December 14, 2012 at 1:38 pm

    my vet told me to wait, i waited and thank god it was afatty tumor.i decided to leave it alone because he is 8yrs old and it dosnt appear to be bothering him..did i do the wrong thing? i just hate to have him go for surgery….

    • Dr. Susan Ettinger on December 29, 2012 at 6:18 pm

      As long as its a lipoma, I am okay to leave it. If its getting bigger or bothering your dog, reconsider.
      All my best, Dr Sue

  6. stephanie lilley on December 14, 2012 at 11:28 am

    One of my friends used a Sharpie to draw around the lump to keep track of the size. My vet says after dealing with my dog with MCT that she will never trust any lump again. I know now that what we used to think was normal for old dogs–all old dogs get lumpy–could mean cancer and we could possibly extend their lives if it is removed.

    • Dr. Susan Ettinger on December 29, 2012 at 6:17 pm

      Good advice, I recommend that too. Hard to do on some breeds without shaving the area. Thanks for sharing!
      All my best, Dr Sue

  7. Cheryl on December 14, 2012 at 9:50 am

    My dog was diagnosed with lymphoma last June and given max 4 weeks. I decided to let him have his time without treatment (which I was told wouldn’t really benefit him as he was so ill) and wonderfully and thankfully he is still with me and doing well (eating, enjoying his walks etc). I am now in a state of limbo because I have no idea how long I will have him. Is this length of time usual for a dog given that prognosis? He has some lumps but they don’t seem to hurt when I touch them. Just not sure what the future holds and would be grateful for any advice. Thank you

    • Dr. Susan Ettinger on December 29, 2012 at 6:16 pm

      Most dogs with lymphoma that are not treated live about a month, but as you proved, statistics will never predict every dog. I wish I could predict things for you now, but the best I can say is enjoy each day – each day is a gift – and keep him happy and comfortable.
      All my best, Dr Sue

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  9. Lynne G. Siegel R.N. on December 7, 2012 at 5:37 am

    If it’s infected, then the biopsy results can be interpreted as a false positive. If you treat the infection, and it can’t clear up, because it becomes increasingly resistant to antibiotics, then piercing it puts the dog at even more risk of getting cellulitis and spreading the infection systemically. so then what? you keep treating the infection over and over with continuous culturing, until you reach a point of ordering the strongest antibiotics available, until you think your dog has MRSA or some other fatal flesh eating bacteria, only to find out later on, that it was a cancerous lesion that made your dog immune suppressed. So, then you have 2 issues to deal with, and in the end, neither can really be treated effectively with anything that exists on the market.

  10. Robin on December 2, 2012 at 1:39 pm

    Hi, Just read this article and it’s a great resource to have. Would you mind if I re-posted your 1-2-3 rule on my blog and in our Newfie club newsletter?

    • Dr. Susan Ettinger on December 9, 2012 at 9:47 am


      Not at all, just please make sure to point out this is my recommendation. You can also please provide a link to the blogs. Thanks for sharing!!

      All my best, Dr Sue

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