I might be inclined to get a web cam to watch him, and if I had a peephole in my door, a second web cam to see if the/a neighbor/external noise level, etc. is bothering him. I'd get web cams that record, much as I'd hate to go through all that video, but I'd want to know the full situation since the report the neighbor made is so contradictory to what you know of your Yorkie. Just a thought...
