In December, our thirteen year old border collie, Gene, was diagnosed with cancer. I had noticed an egg-sized lump on the back of her left thigh a while earlier, and decided to ask the vet to look at it. It was almost like a typical fatty lump seen in older dogs, and she already has some fatty lumps. But this one did feel a bit more “rooted” and it had grown faster than I’m used to seeing in benign fatty tumors. A biopsy identified it as a mast cell tumor, which is common in dogs. So, it was removed after Christmas.
What I thought would be a trivial surgery ended up being more complicated. I learned some things about cancer I didn’t know before. I had envisioned that taking out this egg-shaped mass would be fairly straightforward, as it felt very much like a distinct mass right under the skin. But apparently with mast cells, they invade the surrounding tissue in tendril formation. So, when a surgeon extracts the tumor, she is supposed to shoot for a 3cm “margin” of tissue around the tumor, to ensure she removes every cancerous cell. Otherwise, the cancer will return and regrow. So, the chicken-egg sized area turned into more like a turkey-egg sized area to be removed, including the skin next to the tumor. All from the skinny thigh of a lean border collie!
The tumor was in the most common place on female dogs, high on the backside of her thigh, near her vulva. This created difficulty in achieving enough margin when cutting it out, without damaging her vulva or the structures behind it. The vet said she did the best she could to get wide margins, but wasn’t able to achieve the 3cm target on the top side. When they were shaving her to prep for surgery, they noticed a second lump below the first that we hadn’t detected before. Rather than biopsy that, and risk needing a 2nd surgery, I told them to take that one out too. It did end up being a fatty tumor, so was benign.
Normally the vet would remove the nearest lymph node to the tumor, and have that biopsied as well. This would tell us whether the cancer had likely spread. But, the nearest lymph node in this case was inside the body, so could not be accessed.
After the vet cuts out the mass, she sends the whole kit and caboodle to a lab, where a technician images the mass to confirm whether the margins are completely made up of non-cancerous cells or not. This confirms whether or not they “got the whole thing.” Mast cell tumors are then “graded.” Grade 1 is the most ideal, indicating that the cells are clearly differentiated and not likely to be malignant. Grade 3 is the worst, with low differentiation and high risk of metastasis, and grade 2 is somewhere in the middle. Thankfully, Gene’s was a grade 1 and the lab confirmed there were clean borders around the extracted mass. She has a good prognosis going forward.
I’m not a big fan o fusing traditional “cones” to keep dogs from licking their sutures. Border collies are so sensitive, that making them wear a cone usually causes them to completely shut down and not even attempt to walk or move around. When I’ve had my dogs spayed in the past, I had good luck safety pinning a large t-shirt or nightgown on them to keep them away from the sutures. This one was a little harder, we ended up finding that a combo of vet wrap and a pair of men’s underwear with a hole cut for her tail worked best to keep the incision covered. She (mostly) respected this barrier, though I caught her a few times at night snorkeling her nose under the wrap and sneaking in some licking. Gene is an obsessive licker, she licks fabrics and surfaces, and is always trying to lick us on our skin or in our faces. Her whole life, we’ve always been yelling “Gene! Stop licking!” She knows what this means, so I could remind her even while I was sleeping to stop. licking. Ugh.
The incisions healed nicely, with fur regrown; and she’s back to normal after seven weeks. I imagine it takes time for the skin to stretch back out after being “purse-stringed” around a large void; and surely she lost some muscle tissue there as well. We went to the coast last weekend to harvest razor clams. Watching her run on the beach, a slight alteration in her gait was still barely perceptible, but she seemed mostly recovered and back to her old self. After losing Bronte so tragically and rapidly to cancer last year, it was nice to be given a “pass” on this one!