Dog microchipping: how it works, cost and keeping it registered

Dogs slip out of open gates, bolt during fireworks and wriggle out of harnesses on hikes every day. The ones who make it home fastest usually have something in common: a microchip that’s registered with up-to-date contact information. Dog microchipping is quick, inexpensive and one of the most effective ways to get a lost dog back.

There are plenty of myths about it, though: that it tracks your dog by satellite, that it stores your address, or that once it’s implanted you’re done. This guide covers what a microchip actually is, how it’s implanted, what it costs, the rules in the US, how to keep your registration current and what to do if you find a lost dog.

What a dog microchip is (and isn’t)

A microchip is a passive transponder about the size of a grain of rice (roughly 12 mm long and 2 mm wide), sealed in biocompatible glass and placed under the skin. It has no battery: it sits inactive until a scanner sends a radio signal, and then it responds with its ID number.

Most chips used today follow the ISO 11784/11785 standard, operate at 134.2 kHz and carry a unique 15-digit number. Older chips in the US may use a shorter code and a different frequency (125 kHz), which is why vets and shelters use universal scanners that read several types.

If you want to track your dog in real time, you need a GPS collar, which runs on a battery and often requires a subscription. It’s a great add-on for escape artists, but it doesn’t replace a chip: collars come off, microchips don’t.

How a microchip is implanted

A veterinarian (or trained shelter staff) implants it with a special needle during a regular appointment, with no anesthesia needed.

1. They scan your dog to make sure there isn’t already a chip.
2. They scan the new chip before implanting it to confirm it works and matches the number on the package.
3. They inject it under the skin, in the US usually between the shoulder blades.
4. They scan again to confirm it reads.
5. They give you the chip number and registration information.

The needle is a bit larger than a vaccine needle, so some dogs flinch, but the discomfort lasts seconds. If your dog is being spayed or neutered, the chip can be implanted while they’re under anesthesia.

Complications are uncommon: mild, temporary swelling, a chip that shifts slightly from where it was placed or, rarely, an infection or local reaction. Veterinary organizations agree the benefits far outweigh these risks. Ask your vet to scan the chip at each annual exam to confirm it still works.

Does a microchip really help lost dogs get home?

Yes, when it’s registered. Data highlighted by the AVMA from a study of more than 7,700 stray animals in US shelters found that dogs without microchips were returned to their owners about 22% of the time, compared with about 52% for microchipped dogs. The same research found that only about 58% of microchipped animals had their chips registered in a database, which is the weak link in the system.

Is microchipping dogs required in the US?

There’s no federal law requiring dogs to be microchipped in the US. Some cities and counties do require it, and many shelters and rescues microchip every dog before adoption. Many breeders also chip puppies before they go home.

Microchips do become mandatory in some situations:

• International travel: many countries, including EU member states, require an ISO-compliant chip, implanted before the rabies vaccine counts for travel. For details, see our guide to flying with a dog.
• Entering the US: the CDC requires every dog entering the country, including US dogs coming home from abroad, to have an ISO-compatible microchip.

Even where it isn’t required, the AVMA and other veterinary groups recommend microchipping every dog. It’s also separate from your local dog license, which many cities and counties require on its own.

How much does it cost to microchip a dog?

Implanting a chip typically costs $25–$75, depending on the clinic and region. Shelters and nonprofits often hold low-cost microchip clinics, and adoption fees usually include one. Some registries are free, while others charge a one-time or yearly fee for extra services. It’s one of the smallest first-year expenses, as you’ll see in our breakdown of the cost of owning a dog.

How to register the chip and keep it up to date

In the US there’s no single national database: chips are registered with the manufacturer’s registry or with independent registries. That’s why registering is a step you have to take yourself.

• Register right away with the chip number your vet or shelter gave you. Don’t assume the shelter or breeder did it in your name.
• Update your details whenever you change phone numbers, addresses or email.
• Add a backup contact, such as a relative or friend who lives nearby.
• Transfer ownership when you adopt or buy a dog that was already chipped.
• Report your dog as lost to the registry if they go missing.

Not sure where your dog’s chip is registered? The AAHA Universal Pet Microchip Lookup tool searches participating registries by chip number and tells you which one holds it.

Along with the chip, always keep an ID tag with your phone number on your dog’s collar or harness. Whoever finds your dog can call you in minutes, no scanner needed. Double-check both before the Fourth of July and New Year’s Eve, when more dogs run away, as we explain in dog afraid of fireworks and thunder.

What to do if you find a lost dog

1. Approach calmly without chasing: crouch sideways and talk softly. If the dog seems scared or aggressive, don’t force it, and call animal control.
2. Check for an ID tag and call the number.
3. Get the dog scanned at a vet clinic, shelter or animal control. Scanning takes seconds and is usually free.
4. Let them contact the owner: the clinic or shelter can look up the chip with the registry, which will reach the owner. Registries generally won’t give out owners’ personal information.
5. If there’s no chip, file a found-dog report with your local shelter and animal control, which can tell you the rules where you live, and post a photo in local lost-pet groups.

Frequently asked questions

Does microchipping hurt dogs?

Your dog will feel a quick pinch that’s a bit sharper than a vaccine, because the needle is larger, but it’s over in a moment and most dogs forget about it right away, especially with a treat. No anesthesia is needed. If your dog is sensitive or is having surgery anyway, the chip can be placed during their spay or neuter.

Can a microchip be removed or replaced?

It’s rarely removed: it’s designed to stay for life, and taking it out requires minor surgery. If a chip fails or can’t be read, your vet can implant a second one and you can link the new number in your registry. What does change, and must be updated, is the contact information tied to the number.

How do I find out who my dog’s chip is registered to?

Ask your vet to scan the chip, then enter the number in the AAHA Universal Pet Microchip Lookup tool to see which registry holds it. Contact that registry to confirm the details on file. If you adopted or bought your dog and the chip is still in someone else’s name, request a transfer as soon as possible.

Will my dog’s microchip work in other countries?

If it’s an ISO-compliant 15-digit chip, scanners in the EU and most other countries can read it. If your dog has an older non-ISO chip, some destinations require a new ISO chip or ask you to bring your own scanner. Keep in mind that registries are national or private, so a vet abroad may read the number but not see your details, so travel with an ID tag showing your phone number with the country code.

Sources

• American Veterinary Medical Association (AVMA): microchipping of animals FAQ and policy.
• American Animal Hospital Association (AAHA): Universal Pet Microchip Lookup.
• Centers for Disease Control and Prevention (CDC): requirements for dogs entering the United States.
• World Small Animal Veterinary Association (WSAVA): microchip identification recommendations.