Emotional. He was caged, hoarded and abused for the first year or more of his life. An ugly hoarding situation. Most likely wore a shock collar to discouraged barking, whining, etc.
I know he can bark because he'll sometimes yip or whimper in his sleep, but never when he's awake. He came to us as an extremely skittish, avoidant, essentially terrified animal who was characterized as "shy." Talk about an understatement...
He's not what we'd hoped for or expected, but we're doing the best we can with him. A big plus - there's not an aggressive bone in this dog's body.
He seems to look forward to our little grandson's days here and is extremely tolerant of him.