Anything we can do to a rat we can do to a human.

A microchip is an identifying integrated circuit placed under the skin of a dog, cat, or other animal. The chips are about the size of a large grain of rice and are based on a passive RFID technology.

Microchips have been particularly useful in the return of lost pets. They can also assist where the ownership of an animal is in dispute.

Animal shelters and animal control centers benefit from microchipping by more quickly and efficiently returning pets to their owners. When a pet can be quickly matched to its owner, the shelter avoids the expense of housing, feeding, providing medical care, and outplacing or killing the pet. Microchipping is becoming increasingly standard at shelters: many require all outplaced animals to receive a microchip, and provide the service as part of the adoption package.
-http://en.wikipedia.org/wiki/Microchip_implant_%28animal%29

And we can do pretty much everything to rats.