So sorry to hear that your son's boxer is missing...did she have a collar on w/i.d. tag? I really hope she turns out soon. Did you read the sticky:
http://www.yorkietalk.com/forums/gen...st-yorkie.html
Maybe since she was visiting...if she got loose somehow, she'll need some guidance coming back home. Hang up your son's t-shirt...something that smells like him.
If indeed someone took her...hopefully they'll have a change of heart & advertise somewhere that they found her.