This discussion has come up a few times relating to a few different situations.
The question: Would you rather have time to say goodbye but have that person (or animal) suffer or would you rather they went quickly but you got no time to say goodbye?
I'm still up in the air on this one. My grandfather lingered on for months longer than he probably should have. His quality of life was not good and the strain that his illness put on my grandmother was readily apparent to all who entered their house. However, she was able to make her peace with him dying and got to say goodbye.
My parents had a beloved dog that went to sleep one night and didn't wake up the next morning. It was a painless and quick death for the dog but my parents were devastated over his passing and never got to tell him goodbye.
Selfishly, I think we all want the time to say our final goodbyes...