I have been down this road many times. It will always hurt. Last May I had to put my Billy down after he was bleeding internally. He was 11. I was with his mother when he and all his siblings were born in my Garage. He was an English pointer. He and I drove from eastern Canada 5 times to hunt pheasants in Iowa. As with you and your dog he never let me out of his site. At my fishing camp he never let me sleep alone. He even managed to chase Mrs Weed to the other bed lol, She loved him as much as I did.
After 2 weeks I couldn't take the going to look out the window to check on him any more. I started looking for the Titan's Little BooBoo you see in my avatar. I love her lots, she is not Bill or Dolly or Dan or Ricky or Ginger or any of the others but she is BooBoo and I love her more every day. I wake up early every morning and she is waiting for me.
We dog owners love our dogs because they give us their unconditional love. If you leave the house and come back in 10 min or 10 hours it makes no difference to them they are just happy we are back.
Weed and BooBoo!