As silly as this sounds, you could try what they tell parents with kids who have this issue. Walk outside, close door. Wait 5 minutes. Walk back in. repeat several times a day. (evenings too). After a week, move it up to 10 minutes. Next week 15 minutes, etc. I had a screamer every time I left the house. This trick worked for her, so it should work with a dog, and you don't need a sitter for the dog! I used the time on the front porch, to read. For the dog, you could also walk all over the porch barefoot to put your 'smell'' where he can find it. Also, if you carry small treats when you leave, and give just one when you come back in, your leaving becomes a 'good' thing. This worked for my sister's Chow.