how do you decide when the quality of life drops on a pet. it seems my girl (not my wife) is starting to go down hill. i cant decide where the bottom of the hill will be. there is nothing vets can do because she is 14 years old. she can do ok being deaf. she always did respond to hand commands. How does one decide when its time. my thinking is when dhe can no longer do what a dog does. she is close to that now.