I agree with the others. I'd be a little fearful leaving my tiny Yorkie with a larger dog. Ive been feeling the same with Meka, and we are thinking of getting a kitten....maybe thats a route you might want to consider.
I wanted to ask, does your baby have free run of your house when your away? Because from what Ive read and experienced, he shouldnt just yet. Also, maybe getting him more interactive toys, and try leaving the TV on when your away. I think it helps them not feel so loney - JMO