Microchipping is a modern tool used to help reunite lost pets with their owners. To have your dog microchipped, a vet must implant a tiny chip (about the size of a piece of rice) under the dogs skin at the shoulder. If the dog is ever lost or picked up by an animal-control officer or shelter, he can be scanned with a handheld scanner, which reads identifying information stored in the chip.
One problem with microchipping is that not all microchips are readable by all shelters and veterinarians because the chips require different scanning technology.
Another way to keep track of your dog via technology is by attaching a global positioning system device on his collar. GPS devices aren't cheap (they presently cost several hundred dollars), but its a good way to always know where your dog is. Each unit consists of a GPS receiver and a modem.
When you want to find out where your dog is, you contact a control center that can track him. With some GPS units, you just dial a phone number, and a text message is sent to your phone automatically!