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

Staying Vigilant with Mass Aspirates

Updated: November 21st, 2019


Should you really get EVERY lump checked? Dr. Susan Ettinger, DVM, Dip. ACVIM (Oncology) explains why we should all stay vigilant with mass aspirates and get everything checked.

I am a huge advocate of aspirating every lump and bump on your dog, even though many turn out to be benign cysts or lipomas (fatty tumors). The story below will illustrate why I’m so vigilant, but first, a little about mass aspirates.

Mass Aspirate: What Is It?

When there’s a lump or bump on the surface or just under your dog’s skin, and you can feel it, you should get it aspirated. It’s a simple test, and no anesthesia is required. A very thin needle is put into the lump, and then whatever fluid is inside is drawn up into the syringe, and your vet or a lab can take a look and see what’s in it. This is a really simple screening test for many types of cancer. If something problematic turns up, you can move quickly to address it.

On the other hand, if the masses are benign and not bothering your dog, they probably do not need to be removed: I typically recommend leaving them alone and monitoring them in the future. Perhaps I will recommend surgically removing them at the same time as another procedure like dentistry, but I will rarely recommend removal if the aspirate was benign, because going under anesthesia has its own risks, too.

Your primary care vet and you are on the front line of skin and subcutaneous mass monitoring. Dogs usually come to me, the oncologist, after the aspirate or biopsy has been performed. They either already have a diagnosis of cancer, or at least suspicious for malignancy.

Why They Matter

Here’s the story I promised, and why I’m so vigilant about aspirates for my own patients.

One of the ways I give appreciation to my wonderful oncology nurses is by monitoring the health of their pets. It’s my pleasure to care for them, including aspirating any lump or bump.

One of my nurses has an amazing white Pitty (Pit Bull), named Smokey, which I adore.  I have aspirated numerous skin masses on numerous occasions over the years. And until two weeks ago, the masses have always been fatty deposits.

When my nurse mentioned she was bringing Smokey in to check out a new mass earlier this month, we all expected it to be the routine:  quick aspirate, fat on the microscope slide, document it in is his records, give a treat to Smokey, collect some wags and kisses, and on his way. Actually the day she 1st brought him in was an insane clinic day that kept us all on the move, shorter lunch breaks, overtime for the nurses … and I missed storytime with my two boys. We never did get to Smokey. No worries, my nurse said. She would bring him in on Monday.

On Monday I did my exam. Smokey had a 5 cm mass that was deeply attached to the underlying tissue on his left flank area.  As I did my aspirate, I could see blood collecting in my needle and syringe. I immediately knew this was not a lipoma.  I aspirated the mass in a few more areas, and we submitted the slides to the lab for cytology.

I asked, but there was no history of trauma to explain a mass with blood inside on his trunk.  I told my nurse my clinical hunch was a blood vessel tumor: either a benign hemangioma or the malignant version, hemangiosarcoma. Tears welled up in her eyes, and Smokey became concerned that his mom was upset. My nurse deals with cancer in dogs and cats every day, but it is so different when it is YOUR dog. I could see her mind start to race and shut down at the same time. I gave her a huge hug, and we waited anxiously overnight for his cytology results.

Soft Tissue Sarcoma

The aspirate came back: it was a soft tissue sarcoma. I reminded her about soft tissue sarcomas, or STS. They develop in a variety of connective tissues, muscles, and fat. They can be found in sites all over the body, from head to trunk to paws. The majority of these tumors are usually aggressive locally, which means they invade the neighboring tissues. They are also prone to recur if they are not removed with wide margins. The good news is that the low and intermediate-grade tumors typically don’t metastasize, or spread.

For more tools and information, get a copy of the Dog Cancer Survival Guide

I know it’s weird to hear me say this, but if you had to pick a malignant tumor for your dog, this is a pretty good choice. Having soft tissue sarcomas is not the worst-case scenario for your dog. Low and intermediate grades of soft tissue sarcomas are very treatable and have excellent long-term survival rates (some up to five years). The recommended treatments include surgery and/or radiation for low and intermediate grades. And, occasionally, chemotherapy.

Dealing with the Tumor

The next step was a PRE-surgical biopsy to confirm the tumor type and help our soft tissue surgeon appropriately plan the surgery. A biopsy confirmed a low-grade hemangiopericytoma, a type of STS. We had already run blood and urine tests, and we checked for metastasis with chest X-rays and abdominal ultrasound – all clear!

On surgery day, Smokey had a CT scan to determine the extent of the tumor better than we could feel. These tumors are infamous for having tentacle-like projections that can extend for centimeters, far from the main mass. If we aren’t careful and leave the tumor tentacles in his tissues, we would have incomplete margins, which would mean his tumor would be 10 times more likely to recur.

This is why imaging before surgery, as close to surgery as possible, is so important.

The surgeon reviewed the CT scan as Smokey was prepped for surgery. She reported the mass was most likely resectable (she could remove it), but she would also have to move a flap of skin to close the incision once she was done. You see, because of those tentacles, these tumors require 3 centimeter (more than an inch) margins around the tumor. Not just the skin, either — 3 centimeters deep into the body, too.  That is a really big surgery: for a 5-centimeter tumor, the resulting scar should be at least 11 cm (or 4.3 inches).

Happy Outcome

Smokey’s surgery was a big one, but it went well. He spent 2 days in our ICU recovering, and then we waited for the post-surgical biopsy report to come back and tell us how we did.

Well, I got the biopsy report back this weekend. GREAT NEWS: a low grade (grade 1) hemangiopericytoma with wide, clean margins. This is great news because no post-operative radiation of chemotherapy is recommended. We’ll just do regular monitoring of the scar and the rest of his body.

This story illustrates why there is so much information in the Guide about soft tissue sarcomas. Not all stories end this well, and it’s usually because we just don’t realize how important it is to get every lump and bump checked out with an aspirate.

Stay Vigilant About Lumps and Bumps

Just because your dog has had multiple lipomas or other benign masses in the past, don’t get too relaxed. Lumps and bumps are not always benign, as Smokey proved. After dozens of benign aspirates, it only took one to produce a cancer diagnosis. Stay vigilant and have those lumps and bumps aspirated. It’s not a big deal for the dog (think about as bad as a needle) and it is worth knowing what you’re facing.

Smokey had to wait an extra four days for treatment for his cancer because we all got so busy and put his aspirate on the back burner. Do I think the delay was detrimental to his outcome? Ultimately, no — but he’s a lucky dog with an oncology nurse and the resources of one of the best hospitals at his disposal.

So tonight, and every night, play with and pet your dog and take notice of any masses (lumps or bumps) … and get them checked out. No one — not a vet, not an oncologist, and not you — can tell what a lump is just by feeling. And “waiting and seeing” is not a good idea. Get the masses aspirated. Don’t assume it’s another lipoma.  The earlier we find tumors, the better.

To your dog’s health,

Dr. Sue

Further Reading:

Lumps On Dogs: When To Get Them Checked By A Veterinarian

Discover the Full Spectrum Approach to Dog Cancer

Leave a Comment

  1. Rose Kenney on July 11, 2018 at 7:59 am

    Our dog has a lump on his leg and we had a needle aspiration done and it came back benign. Our new vet said that needle aspiration are not always accurate and that we should have it removed. It doesn’t bother him at all, so I am not sure what to do… Would you agree that the only way to know for sure would be to remove it?

  2. Shannon Dearduff on February 23, 2018 at 10:40 am

    I have a 12 yr old chow mix waiting for biopsy to determine if it’s lymphoma and if it is ? Really whats the best outcome and treatment give. His age ?

    • DogCancerBlog on March 13, 2018 at 1:39 pm

      Hello Shannon, thanks for your comment, and we’re sorry to hear about your boy. Please take a look at chapter 40 in The Dog Cancer Survival Guide, because that’s entirely devoted to lymphoma. The treatments range, and the outcomes, too, depending upon a lot of factors — your pathology report will give you some guesses, and your oncologist will be able to tell you more specifics for your dog. But definitely get a copy of the book, which has information on not just the conventional treatments, but also diet, supplements, and nutraceuticals. It’s helped so many of us!

  3. Mark on January 14, 2013 at 11:25 am

    Hello Dr. Demian Dressler..
    Just one question really..
    my dog has an ulcerated malignant tumor & not many days left i assume..,
    Shes on many drugs: gabapentin & tramadol for the pain,
    celephalexin & prednisone for the inflamation & swelling..
    Unfortunately her rear legs are swollen terribly & fluids are colllecting on her underbelly..
    Is there anyway this can be reversed with other meds as she is becoming very dosile and in-active..


  4. Nikki on December 9, 2012 at 8:17 pm

    First, I have to say thank you for sharing Smokeys story. My dog recently had a large mass show up on her shoulder, and we are waiting for her biopsy results to come back. She also seems to have something going on under her rib cage now too, and we are losing our minds waiting. Our vet attempted to doing a needle aspiration, but said he was unable to get anything with the needle so he made about a 5 inch incision to get a piece of whatever this is. He seems very concerned, but of course reluctant to give an opinion at this point. While she was asleep he was the first to notice that there may be something going on in her abdomen, yet another cause for concern. We have no children only our 2 dogs that we spoil. I guess my question is in your opinion what could cause the vet to not be able to get anything with needle? I have been researching, and have found an oncologist to take her to if it becomes necessary.

  5. Oscar's Person on November 18, 2012 at 12:31 pm

    I think it is excellent advice to push for aspirating all new lumps and bumps. It has been my experience that many primary care vets adopt a “wait and see” philosophy. This is especially true if lumps and bumps are a regular occurrence on your dog. This can be a disaster and potentially cost you time in getting the cancer diagnosis and treatment.

    I have a 7 year old Boxer names Oscar. He has a substantial lump on his left rump and took him to the vet as soon as I noticed the lump. She aspirated one sample and examined it on a microscope right in her office. I was so relieved that it was only a Lipoma but I still had this uneasy feeling about the whole thing. He had a benign Histiocytoma removed in the past so I felt like maybe I was just being overly protective. A couple weeks went by and my instincts nagged at me that it was more than just a fatty tumor. I finally decided to get a second opinion and took him into my sister’s vet. He was much more thorough and took 6 samples and sent them to the university veterinary hospital to examine. The very next evening he calls with the news that it is a sarcoma.

    I decided that I wanted to get the biopsy before proceeding even if it meant more than one surgery. Simply because I was thinking the worst case since it was quite a large tumor. Fortunately there is a 6x7inch Lipoma sitting on top of a half inch STS (peripheral nerve sheath tumor)-grade 2. There is no possible way that my regular vet would have caught that unless she stuck the needle in just the right spot. So I guess the moral of my story is that no one really knows your dog as you do. I had nothing to indicate behavior wise that he had anything going on but this tumor just felt intuitively different from the benign ones in the past. So if you suspect there is more going on get a second opinion or push your vet to do more.

    In phone consulting with the vet and the oncologist they have been cautiously positive. From the path report and visual description by the vet that did the biopsy the tumor is small and in an optimal location for full removal. This might not have been the case if I wrote it off simply as a Lipoma.

    Now the verdict is not in yet. I have 2 appointments this week with separate oncologist to find the one I feel the most comfortable with. I will have them do any further tests as needed. So for now I am a guardedly optimistic about his prognosis.

    I just feel nauseous thinking if I had not followed my own instincts how long I could have went before the cancer was discovered.

    • Dr. Susan Ettinger on November 24, 2012 at 5:49 pm

      Oscar’s Person (love that name!)
      I am sorry to hear about the frustrating story of getting answers for Oscar. At least you are on the right track now. Good luck with Oscar, and keep us updated!
      All my best, Dr Sue

    • Dr. Demian Dressler on November 27, 2012 at 11:25 am

      Wow. Thanks for sharing that important story.
      Dr D

  6. Sarah on October 22, 2012 at 3:33 am

    Can a lump be too hard/solid for aspiration?

    • Dr. Susan Ettinger on October 28, 2012 at 5:36 pm

      Rarely, but it is possible. On some aspirates, the cells just don’t “exfoliate” or extract well, and the cytology will be non-diagnostic. So if I suspect cancer and the aspirate was benign, a biopsy is typically the next step.
      All my best, Dr Sue

  7. Rod on October 22, 2012 at 2:11 am

    I say, “never say never” and also, “never say always”. Fine needle aspirations can result in the spread of the cancer, so care should be taken on a case-by-case basis, and if there are other ways of diagnosing the tumor, such as thermography, then it should be considered, before jumping on the FNA bandwagon.

    • Dr. Susan Ettinger on October 28, 2012 at 5:33 pm

      I agree – never say never and never say always! I treat every case like an individual, and this blog is not to replace the one-on-one relationship of your vet and your pet. Still fine needle aspirates are relatively safe and worthwhile, in my opinion, in many cases. When in doubt, see your vet and discuss the pros and cons!
      All my best, Dr Sue

  8. Kathy Huser on October 22, 2012 at 2:01 am

    Two events over the last 18 months — one each with my now 12.5 year-old female spayed Std Poodles — each with a Oncology lesson for me:
    1) Dolly had a small lump on her rear-central back which was examined (manually) by several Vets over 2-3 years with the opinion “nothing to worry about.” Then a new Vet recommended aspirate/needle biopsy — which came back “Probably not cancer.” (Do they ever say “definite” ?), so the Vet did not recommend excision. Then, it
    burst/erupted — and the Vet sent a slide to the Lab. Results: Sebaceous cyst with secondary infection. When it did not improve after a week on Cephalexin, I sought/found a Board-certified Veterinary Oncologist and she recommended excision. Result: malignant trichoepithelomia. Though the excision was complete with clean margins, “small nests of neoplastic cells were found in a few intratumoral lymphatic vessels” , so the prognosis is guarded and the Oncologist expects possible/probable metastasis in 12-24 months.

    Lesson: Aspirates do not always tell the whole story. (Possibly if taken by an Oncologist, who might have tried several sites in the mass ?)

    2) Happier outcome: Something was “off/not right” with Gracie one day coming up on a year ago. Long story short, with x-ray, Emergency Vet found an abdominal mass and recommended immediate ultrasound/action.
    We raced back to Vet Oncologist who said guided needle aspirate was not an option because it would burst the mass on the spleen; odds were malignant hemangiosarcoma. We opted for splenectomy. All clear !!

    Lesson: Odds are odds. Sometimes you get lucky.

    • Dr. Susan Ettinger on October 28, 2012 at 5:31 pm

      Hi Kathy,
      Sorry about the saga of getting Dolly’s diagnosis. Aspirates will sometimes say certain or unequivocal, but there are limitations. Biopsy is considered the standard for diagnosis, but I find aspirates to be a less invasive, less expensive tool to help guide the process. Aspirate just extracts some cells, but a biopsy provides the tissue and that architecture of the tissue is very useful for a more conclusive diagnosis, in most cases. When in doubt, it is best to get a biopsy.
      And good news on Gracie!!
      All my best, Dr Sue

  9. Mulligan Family on October 21, 2012 at 9:38 am

    Just a correction: the sentence “Then we found two small lumps on her neck and leg and took her to the vet the next day” was supposed to be in relation to her losing her mojo and was the reason we took Lulu to the vets in the first place. Sorry for any confusion!

  10. Mulligan Family on October 21, 2012 at 9:08 am


    Thanks so much for making such an informative and helpful website, it’s been of great use to us in the past few days.

    We got back the biopsy results for our beautiful bernese mountain dog Lulu on Friday, and it says she has Histiocytic Sarcoma, of the liver apparently because of the high liver enzymes. Her white blood cells are surprisingly very good. She only went really downhill after the operation to remove the lumps for the biopsy, which was Tuesday. Until then, aside from a loss of ‘mojo’, she seemed fine. After the op, she got an infection, and didn’t eat and barely drank until Friday evening. Then we found two small lumps on her neck and leg and took her to the vet the next day. On friday, when we got the results, our vet wanted to euthanise her, telling us that she had ’24 hours to live’.

    She has exceeded this and is even seeming to improve day by day. In the last couple of days, she’s started drinking well, ingesting liquified foods and has just now began eating chicken! She’s walking well, wagging her tail, enjoying some rides in the car and her breathing is okay, she’s just very tired. We’re giving her milk thistle, various foods and supplements (thanks to your fabulous cancer diet) and we are getting some SAMe and Apocaps tomorrow.

    We want to try and save her; there’s fight left in this girl, she’s only 5 years old. Our vet said chemo would “only buy her a week” but we seem to be buying this through herbal remedies and good food at this rate. Reiki is also seeming to be very beneficial for her. Lulu is a very strange but wonderful dog in many ways, and her immune system seems good. As a puppy she had terrible demodex and we were preparing for the worst, but she bounced back suddenly. What would you recommend is the best course of action? If she continues to improve this way, it seems it would be a waste to not try some form of medical treatment. She is not distressed by vets at all, and always co-operates well with any treatment.

    Your words of advice would be much appreciated- they have already helped us greatly!

    Kindest Regards,

    Tim, Maria, Katie and Amanda (and Lulu)

    • Dr. Susan Ettinger on October 28, 2012 at 5:24 pm

      Dear Mulligan family,
      Sorry to hear about Lulu. Have you been to an oncologist? While this is an uncommon cancer, it is more common unfortunately in Berners. While it is not one of the 12 tumors I wrote about in the Guide, there is info on Lomustine, which is the chemotherapy of choice for this cancer. There are other drugs that work too, but with Lomustine the median survival time is 6 months. Not great, but more that what you are being told. Granted I have not examined Lulu or seen her lab tests, but there are treatment options. This month, one of my Berners is celebrating her 1 year anniversary since diagnosis. So there are survivors. I hope you you consider a consultation with a specialist. If you need to find an oncologist, check out http://www.acvim.org and click on find a specialist. Good luck!
      All my best, Dr Sue

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