You did the only thing you could do, as a Guardian and Momma of your sweet Krypto, to ease him into "that which follows" where he is free of pain and restored (and that's what I believe! I'm gonna be soon p*ssed off if I'm wrong!)
We take on the pain of loss, and the guilt of being the one to say "it's time" so our babies won't have to live with unrelenting pain, joints that rub together bone on bone, pain that is not relieved by medication or acupuncture or Chinese herbs, or special food, or massage therapy, etc. "I wrap his blanket around it and I sleep with him. I know it sounds weird but I don’t care, that what I’m doing. Krypto’s favorite spot was on my bed and it was my favorite place to have him all cuddled up and comfy." this myself! I have his soft terrycloth towel ready, along with his favorite squeaky toy (An aside: it was heartbreaking when he stopped playing with it because he could no longer hear it squeak. He could only hear loud and low noises from then on). I fully intend to have him sleep in my bed, as usual, every night of his life. ^^^^^ OMG, it's as if I wrote I called the vet's office today and asked when Luigi's *remains* would be ready for me to pick up--I couldn't even get more than three words out before I started crying on the phone. She checked and said she thinks he'll be there tomorrow but she'd call to let me know when he's there--it might not be tomorrow. The depth of my pain is reflective of the depth of my love, and often, I can barely hold it together in public without doing the ugly cry. I feel for you, my heart breaks for you, and for us all.
Heaven is the place where all the dogs you've ever loved come to greet you.