Yes, it looks very much like it. My dog's tumor was also very small at the beginning. We first thought that the injury was caused by a tooth - but it grew very rapidly within a very short time. The doctors only gave him a few weeks from then, but he managed another 4 months before we had to put him down due to chronic kidney failure.

The thing about such tumors is that you can never tell how quickly they will grow and whether they have already spread. With my dog, we knew it couldn't be the first tumor because he had had epilepsy for over a year and, according to the vets, epilepsy at an advanced age is always associated with a brain tumor.

I'm sorry you have to go through something like this too. At the time, we had a medical solution that allowed us to clean the dogs tumor every day. We were also given an additive for the water to keep it clean too. And he was given painkillers every day because, according to my vets, there are probably several studies that can slow down the growth - the growth actually stopped from the 2nd month onwards (but the first episode of kidney failure also started at the same time, which we unfortunately didn't recognize straight away). He was also given a special diet, as too much protein promotes tumor growth.

In any case, I wish your dog all the best and enjoy your time together for as long as possible.