if the dog were at home for long periods, would a dog walker be an option? It would give him a break and he'd have the opportunity to have a relationship with another human.

I walk a golden retriever three nights a week while his humans work in the resturant industry. Dog gets a nice walk mid evening, and we've become quite fond of one another. When I meet him on the street (he lives right next door), he does his happy dance to see me. I think it's a great solution to being home alone for a long time.