[Update] Our experience treating oral melanoma in our senior dog
I wanted to share this experience about our (now passed) dog who had oral melanoma for future pet parents that run into this in their own lives. If that's you reading this now, I'm so sorry. Cancer sucks. We loved the heck out of our dog and it has been gutting to be on the other side of it now, but I wanted to provide something useful for others in the wake of this. I am not a veterinarian by training, but I am a researcher/statistician by training and did use that skillset throughout this.
Diagnosis
This year, in February, I noticed our 14 year old jack russel-chihuahua mix had a growth along the outside of her teeth when she was panting. We had noticed weeks earlier that her breath had started smelling really bad, but didn't notice the growth or realize that it was related (it was). Immediately, I got her into her veterinarian to inspect it. They weren't 100% positive if it was malignant, but were suspicious that it was cancerous so referred us to an oncologist at BluePearl.
In between, I spent a ton of time reading about oral tumors in dogs and stressing out about the type of tumor she had and what we would do about it. I learned that the closer the tumor is to the front of their snout, the less risk of metastases there is. This gave me some optimism since her tumor was about midway between the front of her snout and where her lip ended, if that makes sense. I also felt that most of the treatment options were actually somewhat decent no matter what kind of tumor it was.
Our original appointment with the oncologist was about a month away, but they (unfortunately) have frequent cancellations and were able to get us in sooner. The doctor took a small biopsy of the tumor and her lymph node to confirm the type of cancer. They also told us the approximate size of the tumor, which was around a stage 2 or stage 3 by definition despite still being pretty small. The oncologist at the time told us she suspected it was either a squamous cell carcinoma or a melanoma, but needed to get the biopsy to be certain.
The biopsy came back after around a week, where they confirmed it was an oral melanoma. This is the most aggressive and most common type of oral cancer in dogs. The biopsy also revealed the mitotic index of the tumor, which is a rough measure of how quickly cells are dividing and replicating. Her tumor's mitotic index was above the 4 number that signifies more aggressive cancers, but her oncologist said that hers was still a bit on the lower side that she'd seen for oral melanomas. The exact measure was 30 mitotic figures per 10 powered fields, which is still very concerning.
Treatment (Partial Mandibulectomy, Oncept)
The best option presented to us was surgical removal of part of her jaw (partial mandibulectomy) and the closest lymph node. It sounds pretty terrifying at first, but the oncologist showed me some before and after photos and you can't even tell that a lot of these dogs have had surgery other than their tongues hanging out haha. They also told us that after her surgery she would be eligible for the immunotherapy called Oncept, which is a vaccine that teaches their body to fight the cancer.
I read all of the studies that are out there about the surgery and about Oncept. The few papers out there about Oncept gave me a lot of hope. It seems to be very safe, can be effective in dogs, and seemed to even be curative in some. There were some dogs in a study that, after taking Oncept, outlived the study period, which was 1-2 years long. However, I can say our oncologist was not super optimistic with the results she had personally seen using Oncept. The biggest issue is that it is very expensive. The shot+administration was close to $1,500 each time, and they recommend a series of 4 shots right after surgery, with boosters every 6 months. The surgery itself was around $6,000 if my memory serves, so we were looking at a $10,000 bill by the end of treatment.
We decided to go for the whole thing, since our dog was in pretty good health otherwise despite her age. We were fortunate to be able to afford it all but it definitely set us back. So all within the month of February, our dog was diagnosed, had surgery, and had had her first shot of Oncept.
Post-Surgery
The surgery went smoothly, they kept her overnight just to make sure everything was okay afterwards and to allow her to adjust. We hated not having her home but these dogs are in a pretty rough state immediately post-surgery and need quite a bit more medical care than is safe to do at home. When I picked her up from the hospital, she was drooling blood all over the place and was exhausted, so I recommend bringing a towel with you for the ride home.
I won't lie, the post-surgery period was some of the toughest weeks of pet ownership I've ever experienced. The dogs have a million post-surgery medications, they have to basically re-learn how to eat and drink, they drool everywhere, you're afraid to force anything down their throat because they JUST had jaw surgery and stitches/wounds are still fresh. The part that made it the hardest though, and one of the things that inspired me to share this story, is that our dog would not stop regurgitating food. She couldn't keep anything down. She would regurgitate mostly overnight, food, bile, basically anything she ate got regurgitated. This is a normal symptom from being intubated and if it gets bad it creates a really vicious cycle.
One of her medications she was prescribed, omeprazole (Prilosec), was supposed to help with her regurgitation. As we approached the end of 2 weeks of regurgitation hell, we stopped giving omeprazole because it was only prescribed for 2 weeks. This radically improved the symptoms, and afterwards I learned via researching it that one of the side effects of omeprazole can be regurgitation, ironically. So check ALL the side effects of all the medications they give you!
Slowly, our dog adjusted. She re-learned how to eat, although it was SO much messier, and she slopped water everywhere. But she was happy and adjusting. We got a biopsy of the fully-excised tumor and lymph node back that showed good margins and that the tumor had a mitotic index of 21 (lower than the original biopsy) and that the cancer had only just barely started to enter the lymph nodes, but it was in there. This gave us some optimism.
Cancer Returns and Spreads
After her final course of Oncept, we had a couple great months with her. She was pickier about eating, which I didn't blame her for lol. However, we noticed that the area where her lymph node used to be started to swell in size, to a pretty large lump, and her tongue started to hang out the side less and less. Her cancer returned. It came back as another tumor in her mouth, this time on the inside of her lip, which was holding her tongue more inside her mouth than before, and seemingly in her lymph node.
Then, she started breathing much faster, and, thinking she was going into heart failure, I brought her to the emergency vet. They said her heart was fine, but we decided to do x-rays of her chest at her primary vet to see what was going on. We found out the cancer had spread to her lungs.
We informed the oncologist, and decided we wouldn't do another surgery. The oncologist seemed to think the Oncept wasn't really working for her, or had only been working short term. However, she also said and I had read that it takes a few months to fully kick in. We decided to start her on a chemotherapy pill that is supposed to have minimal side effects (chlorambucil). We only gave it to her for a few days, but it started making her rergurgitate and have zero appetite so we quickly decided just to stop giving it to her.
Over the summer months, the tumor in her mouth seemed to basically stop growing and the one near her lymph node actually shrunk in size. She was breathing faster than she used to, but didn't ever really get out of breath or cough much. However, her appetite continued to be very poor and she had been losing weight, from 21 lbs originally down to 17 or so. She started getting to the point where her ribs were showing. We were trying everything, hand feeding, making her human food, anything to get her to eat, but nothing seemed to stick.
The Downturn
We had an appointment with her oncologist and kind of described everything going on. She was due for her Oncept booster in just one month, and she said there was no harm in getting it early, so we did. We got more x-rays, and they showed that her lung tumors had not really increased in size much at all, but there may have been smaller ones popping up not visible on radiographs. Her Oncologist was pretty pleased with her status, and while caring for her was a bit of a chore, things seemed okay overall and doggo seemed happy.
The day following her Oncept booster, we also got her a Librela injection from her primary vet for arthritis pain. She had had it multiple times and it really seemed to help her. For some reason, and it may have been related or unrelated to the Oncept and Librela, she started to take a turn for the worse. She didn't really want to walk long distances anymore, she seemed more depressed, and she started having more accidents in the house, almost like she couldn't control it. Then, her breathing started to become so bad that it seemed like she was in distress. Lastly, at the same time, this thing started happening where she would start walking sideways. We had no idea what to make of that. She started laying outside, switching between the sunshine and hiding behind trees, for most of the day unless we forced her inside, and she stopped eating entirely.
We had her primary vet prescribe her prednisone to see if it could bring down some of the swelling in her lungs that might have been causing her breathing distress while we planned her euthanasia. The prednisone seemed to help a good amount, and she had a pretty decent day the next day. That night my mom had tickets to a baseball game 2 hours away, and we had my sister-in-law and her husband watch our dog. They left about 2 hours before we got home, and we were watching our dog on our pet camera, and all seemed to be fine. Even 30 minutes before we got home, she was up and sniffing around. When we got home, she was in her dog bed, looking like she was peacefully asleep. We didn't immediately notice, but she wasn't breathing. I called the emergency vet, and they walked me through checking her vitals. She had passed away in her sleep.
Aftermath
We don't truly know what happened. Her oncologist seemed to think, especially after describing her walking sideways and having frequent accidents, that she was having strokes and likely had a stroke in her sleep that ultimately killed her. She had cushing's disease as well as cancer, both of which elevated her risk of stroke, and we had also given her prednisone which seems to increase the risk too. It's not 100% certain, and if you have any advice or thoughts I'm open to hear it, but this seems the most likely to us.
My partner and I don't regret anything that we did. We did the best we could with the information we had at the time. We are relieved that she isn't suffering anymore and that she got to go out in peace on her own terms rather than via euthanasia. We miss her a lot though - she was the most special pet we've ever had.
Thanks for reading, and I hope this was helpful. Even if this post is very old when you find it, don't hesitate to comment or message me and ask for any advice. As I said, I'm not a veterinarian but I can maybe help give some guidance or support if you need it.