John...I agree with you about dogs feeling a sense of lose and depression. Our Owen had a lot of stress & anxiety when our first few sharpei passed away. He also perked up when we got Bailey (his previous owner's house burnt down and they could not keep him). Owen needed dog friends. When Owen passed away last spring...Spanky seemed out of sorts for a long time because they were buddies and did a lot of daily activities together. So...animals do form their own relationships and bonds with one another.
Our Bailey had been a very welcoming and calming influence on new dogs coming into the house. We just wish he got more respect...we call him the Rodney Dangerfield of the family.
Because he is mellow and nice...they think they can boss him...but he does have an impressive growl when he has had enough.