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Featuring Demian Dressler, DVM and Sue 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

Leave a Comment

  1. Fran on January 5, 2021 at 9:07 am

    My dog is 6 we just noticed a lump on her right side by her rib cage. My Vet said a fine needle aspiration might be to hard to do because of the muscle . So she recommends surgery. I’m not sure I want to do that I would like to do the aspiration first. Please HELP!

  2. Jan on December 9, 2020 at 2:09 am

    My dog has two lumps which have been diagnosed as fatty lumps. I have been told by the vet to leave them be but one of them is quite big and on the upper right front leg on the inside. He is an active 10 year old boarder collie and I think the lump is uncomfortable for him possibly rubbing against his body as he doesn’t like me touching it. I wondered if I should get it removed as it in an awkward place.

    Thank you

  3. sasha on May 26, 2020 at 9:42 am

    Hi I had read your article and then i took my dog to get a suspicious lump aspirated on her side by her ribs. But, she never came back the same dog, and then passed away last week from fluid in her lungs. The doctors all insist it was not related to the aspiration, but she was noticeably in pain after the aspiration. She seemed to get better but then got worse soon after. Have you heard of dogs passing away from a puncture or would related to a bad aspiration?

  4. Lisa H Siriani on April 16, 2020 at 10:42 am

    I have a 10 year old Pitty, Caleb,he has been by my side since he was 8 weeks old and I picked him out of the litter at 1 week,well, he picked me by crying this strange cry and crawling to me as best he could.. and it was Love forever from there on…He has a FEW skin tags and he has gotten a couple sebaceous cyst that were hard and went away…Btw he is my service dog I’m a transplant patient and I also have seizure and more…I have now been on Quarantine for months because of the covid 19 virus and my Drs say I cannot leave the house,I’m extremely anxious all the time and I can tell he can feel it ☹️Well two days ago suddenly he had a hard large lump on his chest under his neck , I could move it around under the skin a bit,.I cried and cried and cried, I literally don’t think I’d live without him,I’m losing my transplant and I’m so sick and scared already, I live for him.. this will be my third transplant IF I can get one in time..We went to the Dr but I couldn’t go in with him for the first time ever because of the virus and the Dr called and said she needed to do fine needle aspiration and I asked can’t you miss something with just one poke? and she said yes , she would do multiple was done and she said id have results in a week,.at first I thought the bump went down a little bit now it seems bigger after the aspiration.. is that normal,does it mean something?? she said if it shows benign we don’t have to do anything but if it’s shows malignant cells or inconclusive we will have to remove whole thing..He’s 10 and on neurontin for tremors in hind legs and Dasaquin advanced for arthritis and he gets cyto point injections for skin allergies furnucles with secondary bacterial Infection and we bathe him with chlorahexadine shampoo twice a week and clean ears twice a week and this week I discovered what I thought was yeast in ear and Infection and I was right so he’s on the drops antibiotics too…do you think these two things are in common with the lump.. and do you think it would get bigger from the trauma of the needle, or smaller if it was a cyst??.. Sorry to go on so much I’m so scared for the love of my life.So happy for Smokey and his owner!!Thank you,Caleb’s mom

  5. Mr Martin Goodright on December 28, 2019 at 6:44 am

    Hi there we have a English bull terrier he has a mole that he has been at it and made it sore it then grow in size and has now bleed before we go to the vets was hoping to see if we could get an idea of what we are dealing with. I can send you a picture of it if it helps. Thanks Martin

  6. Néstor Camps on December 28, 2019 at 6:02 am

    I went yesterday for a FNA with Cytology in house: lipoma.
    What kinda of report should I received from the Vet?
    She told me that everything was Ok and that my Pet has not presenting any kind of Cancer.-

    Thank you,

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