How Does a Computer Chip in a Dog Work?

Help me find my home!
i Lost puppy. image by Catabu from

Once a pet becomes lost, it’s likely that he'll stay lost, according to Having a computer chip, also called a microchip, implanted in your pet increases the odds of his being returned to you.

What It Is

Inserting a computer chip into a dog allows him to be traced. The chip is about as big as a grain of rice and is injected just under the dog’s skin between his shoulder blades. Each chip contains a unique identification number that is entered into an international database. Microchips last for 25 years.

How It Works

Once your pet is found, any animal shelter or veterinarian’s office can read the ID number using a microchip reader. This is a handheld scanner that detects the chip and displays the unique number assigned to your pet, which can then be inputted into the database. As long as your contact information has not changed, your pet can be returned to you. It is your responsibility to update the database if your contact information changes.


Many people don’t want to put a foreign body in their pets. Microchips have been proven safe, according to They are made from a biocompatible substance that won’t degenerate or cause an allergic reaction. They also have antimigrating properties so they won’t travel from their injection place.

Computer Chip vs. Collar and Tag

The best protection for your pet is to have him microchipped and to have him wear a collar with a tag. The collar and tag alert people that the lost dog likely has a home, and can be read immediately without any special equipment. The problem with using only a collar and tag is that the tag can become unreadable after a while. Collars can also come off; if your dog is deliberately stolen, the thief can remove a tag in order to sell your pet. A microchip, on the other hand, cannot become lost or unreadable, and provides undeniable proof of ownership if your dog is resold.

Common Concerns

It costs little to microchip your dog, usually around $25 to $40, but some companies charge an annual fee. Statistics from the American Humane Society show that only about 17 percent of lost dogs without a microchip are reunited with their owners. This makes a microchip a cheap insurance policy. It doesn’t hurt your dog when he gets microchipped. It feels similar to getting a vaccination, and similarly requires no anesthetic or hospitalization.

Indoor Pets

Indoor pets need to be microchipped too. Accidents can happen, and your dog could run outside when someone opens the door, or someone could leave the gate to your backyard open. If your lost dog has no collar and tag and no microchip, the odds of getting her back are not in your favor.

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