As for you, Kuro, I know those feels in spades. While it's hard for you, remember that you gave that dog a life that most people would shoot their mother to have ( +/- some people ).
And while it may hurt now, I'd suggest getting another dog. Why? Well, don't think of it as a replacement, right off the back, no. Think of it as you giving another dog a chance of a life time to enjoy things in blissful dog-y-ness