A microchip is a miniture device — about the size of a grain of rice — that’s implanted just underneath your pet’s skin (usually between the shoulder blades). The electronics are housed inside a bio-glass sleeve, which is completely safe for both pets and humans.
When viewed under a microchip scanner, the chip emits a radio frequency that reveals your dogs a special number, like social security number.
A vet, animal control officer, or shelter can look up the number in an online registry and get your contact info and let you know they have your missing pet.
It’s important to note that you must complete the online registry or they will not be able to reach you.
Some great things about using a microchip are:
They last 25 years
They can't get lost or broken in case your tag does
It's quick and relatively painless
The database is national
Your personal information is not available to every random stranger
If your pet is lost or stollen it proves your ownership
A microchip is not a GPS tracker it is only useful if your pet is found or handed over to someone with a scanner.
As far as pain goes it is very similar to getting a routine shot.