
It's a very difficult decision to make. There are so many questions I would need the answer to within reason before I would say what I would do. But I do think I would be inclined to lean towards enough is enough if the dog is in no pain or discomfort. It's a case of knowing when to draw the line and quality of life is very important. Only you can make that decision.
One of mine has a lump on her neck in the dermis of her skin. We found it 18 months ago and at the time it was the size of a pea. Lately it grew to marble size and then to a small egg but now it's gone down again to a pea. There appears to be a stalk attaching it to tissue and we noticed the skin has thickened around it. We keep an eye on it and are careful not to touch unnecessarily. It doesn't appear to have any jagged edges, very smooth and it's not bothering her at all, no pain, nothing. But I'm aware that it could be a MCT but then again it might not. Vet doesn't know. But on the balance of quality of life, Sheba is 10, unaware of it and in great health otherwise. She's not good with vets, petrified of them, starts shaking as soon as she enters the vet's doorway and she's blind which makes it worse for her. I'm reluctant to subject her to surgery for something that may turn out to be benign, then again it might not. It's very difficult knowing what to do for the best. It's trying to balance the quality of life against vet treatment and no doubt that differs from person to person and dog to dog.
Good luck whatever you decide to do.