It is sad to think about. My dog Charlie is only three, but if I lost him I would cry for sure. I mean a dog is basically a human but smaller with fur. They can smell hear see taste and sort of feel. And when your dog spends 10+ years with you, it’s more than losing your friend, like losing your brother or sister. Right now, if I thought about Charlie old blind and deaf, I don’t have the heart to put him down. I know what your going to say, what if he is in pain? Ok. If your human best friend was old and withered, and you had to put him down, would you? Exactly.