I posted this a few days ago...
I found this website with a device that alerts you when your Yorkie leaves a certain area. That might be a great help when it comes to finding your lost baby too.
"The Alert mode enables an invisible boundary to be set around the Loc8tor – near, medium or far, and warns the moment any tagged item goes out of your preset safety zone with an audio alarm, on screen display detailing the item/s missing and a vibration Alert.
Ideal for protecting your possessions whether you've accidentally left it behind, it's been stolen or to inform you that your child or pet has wandered off."
Not quite cheap though...
http://www.loc8tor.com/product_information.asp
We are still praying for little Maddie.....