Six weeks after surgery, Bea had a consultation with an oncologist at Canada West Veterinary Specialists (the same clinic where her surgery was done). They asked me to bring her fasted so they could do blood work and take x-rays, and if all looked good, she would be given her first dose of chemotherapy that day. I dropped her off at 8am and she hopped up to the door, still excited to go there, despite knowing they were leg thieves! It was so great that she didn’t fight going to the clinic. She gets loads of attention there, which is her favourite thing on earth. My sister worked in a vet clinic when she was young and she went to work with her on Saturdays when she was a pup, so she feels at home in vet clinics, which has been so fortunate during the past six months!
Her blood work and x-rays looked mostly good, but we did get a bit of a surprise—there was a single, very small node on one lung, a little under 2cm. When they looked back at the previous x-rays done in August, they could see a shadow in that spot, and because the initial x-rays were done at my family vet, they looked a little different. It was one of those things that going back to the x-rays knowing where to look they could see it, but the radiologist hadn’t noticed it when they reviewed the x-rays two months previous. So this threw a bit of a wrench in the works. The primary spot that osteosarcoma metastasizes to is the lungs, so chances are it’s osteosarcoma, but it’s difficult to say. So far, this node doesn’t follow any rules. Mostly due to the fact that now, six months post surgery (and 8 months since the initial x-rays), there’s still just the solitary node. If osteosarcoma spreads to the lungs, it’s usually multiple nodes, and especially after some time, it can resemble a snowstorm on the x-ray.
The oncologist talked me through the options considering this lump, and I opted to go ahead with the chemotherapy as planned. If this lump was osteosarcoma, then the chemo would likely slow its growth. If it was another type of cancer, we could deal with that when the time came. The reason chemotherapy is done after surgery is because even though the tumour has been removed, the cancer is likely already in the bloodstream at microscopic levels, and small mets on the lungs or elsewhere could be too small to be picked up by x-rays. Giving the IV chemo often slows the spread significantly. Of course every case is different, but by and large, chemo after amputation increases the life expectancy. Fortunately, chemotherapy is often tolerated very well by dogs, it’s not like the chemotherapy given to humans. The doses are lower and it’s often more targeted, and the side effects are much less extreme. The most common side effect is gastrointestinal, like in humans—stomach upset and diarrhea. There can be hair loss, and muscle weakness in some cases. Fortunately, Bea experienced none of these. She lost a few whiskers, and some broke off due to brittleness, but her coat remains as ridiculously thick as ever, and during treatment her hair grew back in over the wound site in its typical lush fashion.
Bea received Carboplatin, which is the most commonly used drug to treat osteosarcoma. It is sometimes paired with a second drug called Doxorubicin, but our oncologist has found that the addition of Doxorubicin doesn’t significantly increase the efficiency of the Carboplatin but it does often increase the side effects, so she prefers to treat with Carboplatin alone. They have found that they get the same outcomes as they did when using both drugs, but have far fewer gastrointestinal issues. Because Bea’s kidney numbers have tended towards very early kidney failure (though they have showed this for more than 3 years without change, so it seems like this may simply be her “normal”), they wanted to start with a slightly lower dose to make sure it didn’t adversely affect her kidneys. She was given the dose of 250mg/m2, the m2 means square metres, so the surface area of the dog, which is calculated by their weight. They then did a blood test after 9 days and 16 days, to make sure her white blood cell count didn’t drop too low. If it drops below a certain level, antibiotics are given to prevent infection. Bea’s levels did drop as expected, but stayed within normal range. Carboplatin is given every 3 weeks, for either 5 or 6 doses. Again, our oncologist has found that six doses vs five doesn’t improve outcomes, so we did 5 doses. They did increase the dose to 275mg for her follow up appointment, then to the recommended 300mg/m2.
She experienced no side effects, aside from her leg feeling weird the first evening after receiving the dose—they alternated legs, and I found this mostly after the sessions where it was administered in her front leg. It didn’t seem to hurt, I think it just felt weird. They sent us home with Cerenia which is an antinauseant, which was given for 4 days after chemo. This is to pre-emptively treat any possible nausea, as nausea is much easier to control if it’s treated beforehand. Like pain, trying to get rid of nausea once it has broken through is much more difficult than using meds to avoid it in the first place, if possible. They also gave us metronidazole, an antibiotic that’s great for stomach upset, as it kills bacteria but also soothes the digestive system. We didn’t need to use it. We got a prescription for mirtazapine which is an appetite stimulant, which I assure you Beatrix did NOT need! She was voraciously hungry after her chemo days.
After her final dose of IV chemo, we gave her body a rest for a month, and then started her on Palladia, which isn’t technically chemotherapy—it’s an anti-cancer drug. The difference is that chemo kills the cancer cells, whereas Palladia inhibits the cancer cells’ growth and spread, and also stimulates the immune system to fight the cancer. Palladia is used for mast cell tumours, carcinomas and other cancers, and it is also used to inhibit growth and spread of osteosarcoma as well as histiocytic sarcoma and primary lung cancer, which are the other two most likely causes of Bea’s lung nodule. Histiocytic sarcoma is unfortunately very common in Berners, but it also is notoriously fast-moving, often it has taken over a dog’s system entirely by the time it is discovered, so it’s doubtful that’s what’s happening. Her node still doesn’t fit any profiles, but if it’s cancer, chances are good that the Palladia will treat it. It’s entirely possible that it’s a benign growth as well, but in any case, the osteosarcoma could always come back, and Palladia will likely keep it at bay for longer. She has tolerated it very well in her first month. There was some weakness and stiffness in her back legs during the second week which is unusual for her, so we decreased from 3x per week to every third day for the rest of the month. The stiffness and weakness went away, so it may be unrelated, or it may be that the slightly reduced dose helps. For month two I will go back to the recommended dose of 3x per week, and we will see if the muscle issues return. If they do, at least we know that a decrease helps.
All in all, chemotherapy, like the surgery, was much easier to navigate than I ever would have expected. Bea has had an excellent quality of life, her day to day has barely changed.
Next: Beatrix’s Life Today