J.W.
Perhaps it is my strange way of looking at life but I don't think animals see life as we do. To me this makes it unfair to base decisions on how we feel, what we know.
Both humans and animals have the drive, the will to live, but it is not based on the same criteria. They do not understand quality of life, we do, ya know?
Even then we have the ability to judge an animal's quality of life but even then we can't determine, clearly, what that means to the animal.
I say this because I see to often prolonging an animal's life for the human without consideration for how the animal feels.
One of the hardest things *I* endured was watching my ex mother in law prolong her dogs life. *She* was not ready to let go so she rationalized that he would want to live but he was a dog, he had no idea of life and death, only survival. So for a year I had to watch this dog suffer, a dog that clearly only knew he could not breathe, he could not run, if a dog really had happiness, he was unhappy. She took him for chemo to keep the cancer in his throat from growing and completely constricting his airway. It was inoperable.
Eventually, just before he could no longer breathe at all, she put him to sleep. I saw her only as a cruel selfish woman though it all even when she said she was doing it for her pet.
So I guess I am saying don't look at this from a human point of view. Instead look at how the dog will see things. He understands pain, loss of mobility, things like that. He does not understand this pain will allow him to live longer, walk better, he cannot see the end game, that is a human ability.
Please consider not what is best for you but for the dog.