Dog tracking collar
A dog GPS system - love it! In addition to a chip, this would be most helpful. Though you'd have to make sure the collar was a well-fitting one and not apt to be pulled off somehow.
Here are some good things recommended: [URL removed]
After my old man lost one time, I tried many types of GPS to track him. After trying a lot, I found that PetFon and Whistle are the most suitable for ordinary families with pets. Garmin is good, but too expensive. Their mobile applications and controllers are very easy to set up, and not easy to drop, I can always see where my dog is through the application.