Congrats on the new puppy, also Shadow was my black labs name!! Im glad you took him to the vet and stuff, And my Shadow NEVER grew out of barking, he didn't bark in the house(where he spent most of his time) and he didn't bark much outside, he had a full cable line right across the back yard, he would only bark constantly if the neighbors were outside or if we were outside and not in his reach.

Does he sleep outside?