Thanks again everyone.
I honestly think this is the best thing. I believe he was actually in pain for quite some time. But since he is already such a kickback dog we didn't realize it. So now he is pain free and playing like a puppy with Digger (and all the other pets) at the bridge.
It's going to be difficult when I go up there this Thursday for my nieces graduation and he's not there. I think that's when it will hit me the hardest.