if you want to see some really great videos of dogs like this being rescued check out the hope for paws videos on youtube by eldad hagar. They do some amazing work for dogs like this one
I can understand where your going,the dog was in pain and was miserable most likely due to abuse, BUT the dog can forget the bad past and still have a full life ahead of him/her and enjoy it with the man who saved it from possible death.
May the world reflect this x