What a microchip does and why it matters

A pet microchip is a tiny device, about the size of a grain of rice, that holds your contact information and is implanted under your pet's skin. If your dog or cat gets lost and ends up at a shelter or veterinary clinic, staff scan for the chip, read your phone number and address, and contact you directly. Unlike a collar tag, a microchip cannot fall off, fade, or be removed by accident.

The chip itself does not have a battery or GPS — it is passive, meaning it only transmits information when a scanner passes over it. This is why a microchip is not a replacement for a collar tag or fence; it is a backup identification method that works only if someone finds your pet and takes them to a place with a scanner.

Shelters, animal control offices, and most veterinary clinics have microchip scanners as standard equipment. If your pet is found by a stranger and brought to any of these locations, the staff can identify them within minutes. Without a microchip, a lost pet with no collar has almost no way for a shelter to contact you.

Key Takeaways

  • A microchip is implanted under the skin and contains your phone number and address, allowing shelters and vets to contact you if your pet is found.
  • The implant procedure takes seconds, costs between $25 and $75 depending on your veterinarian, and is usually a one-time expense.
  • After implantation, you must register your pet's chip number and contact details with the microchip company's database, or the chip will be useless if your pet is found.
  • You should update your registration whenever you move or change your phone number, because shelters can only reach you if your information is current in the database.
  • A microchip works only if someone finds your pet and brings them to a facility with a scanner — it does not track location or replace a collar tag.

The implantation process and what it costs

Your veterinarian implants the microchip using a needle slightly larger than the one used for a standard vaccine. The procedure takes about 10 seconds and requires no anesthesia or stitches. Most pets feel only a brief pinch. The chip is placed under the skin between the shoulder blades, where it is protected but still accessible to a scanner.

The cost varies by veterinary clinic and ranges from $25 to $75 for the implant alone. Some animal shelters and rescue organizations offer microchipping at lower cost — sometimes $15 to $30 — during special clinics or adoption events. If your pet is already at a veterinary clinic for another procedure like spaying or neutering, you can often have the chip implanted at the same visit, sometimes at a discount.

Once implanted, the microchip lasts the lifetime of your pet. There is no battery to replace, no maintenance required, and no expiration date on the device itself. The only ongoing responsibility is keeping your registration information current in the microchip company's database.

Registration and keeping your information current

Implanting the microchip is only half the process. When your veterinarian implants the chip, they will give you a registration form or a code to enter online. You must complete this registration with the microchip company — usually within a few days — and provide your name, phone number, address, and your pet's name and description. Without registration, the chip number is just a string of digits with no way to reach you.

Different microchip companies maintain separate databases. The most common ones in the United States include HomeAgain, AKC Reunite, and 24PetWatch, though others exist. Your veterinarian will tell you which company manufactured the chip they implanted. You register directly with that company, not with your veterinarian.

If you move or change your phone number, you must update your information in the microchip database yourself. Shelters and veterinary clinics can only call the number listed in the database. If you move and do not update your address, a shelter may send a letter to your old home, and you will never receive it. Many lost pets are returned to their owners within days, but only because the microchip information was current.

How shelters and vets use microchips to find owners

When a lost pet arrives at a shelter or veterinary clinic, staff scan the animal's body with a handheld microchip reader. If a chip is present, the scanner displays the chip number and the name of the microchip company. The staff member then contacts that company's database — either by phone or online — and retrieves your contact information.

Most microchip companies operate 24 hours a day, 7 days a week, so a shelter can reach your information even outside normal business hours. Once the shelter has your phone number, they call you directly. The entire process from scan to contact usually takes less than 15 minutes.

Some shelters and veterinary clinics also check multiple microchip databases at once using a universal scanner, which speeds up the process even further. However, not all scanners are universal, so registration with the correct company is critical.

Microchips for cats, dogs, and other pets

Microchipping is most common for dogs and cats, but the technology works for rabbits, ferrets, horses, and other animals. The implantation procedure is the same regardless of species. For very small animals like hamsters or guinea pigs, microchipping is generally not practical because the chip is too large relative to the animal's body.

Indoor cats are often microchipped because they cannot wear collars safely and may slip out an open door. Outdoor cats and dogs benefit from both a microchip and a collar tag, since a collar is the fastest way for a stranger to contact you without a trip to a shelter. If your pet wears a collar, make sure the tag includes a current phone number — not just your name and address.

Combining microchips with other identification methods

A microchip is most effective when paired with a collar tag. A collar tag allows anyone who finds your pet to contact you when ready, without needing a scanner. A microchip is the backup — it ensures that even if your pet loses their collar, a shelter or veterinarian can still identify them and reach you.

Some pet owners also use GPS tracking collars or AirTags attached to their pet's collar. These devices allow you to locate your pet in real time if they wander off. However, GPS trackers require a battery, a subscription service, and a charged device on your pet at all times. A microchip requires none of these things and works indefinitely.

The best approach is a combination: a current collar tag with your phone number, a microchip registered in an up-to-date database, and optionally a GPS tracker if you have the budget and your pet tolerates wearing it. Each method covers a different scenario — a tag for a quick return, a microchip for a shelter recovery, and a tracker for real-time location if your pet is lost in a large area.

What to do if you adopt a pet with an existing microchip

If you adopt a pet from a shelter or rescue, the animal may already have a microchip implanted by the previous owner. Before you take the pet home, ask the shelter or rescue to scan the chip and show you the number. Then contact the microchip company and request that the registration be transferred to your name and contact information, or that the previous owner's information be removed.

Some microchip companies allow you to update the registration online; others require a phone call. Do this before you leave the shelter or rescue, or do it within the first few days of adoption. If you do not update the registration and your new pet is found by someone else, the shelter will contact the previous owner instead of you.

If the shelter or rescue cannot provide the microchip number or company name, ask them to scan the pet one more time and write down the information for you. Keep this documentation with your pet's medical records.

Frequently Asked Questions

Does a microchip have GPS or track my pet's location?

No. A microchip is passive and contains only your contact information. It does not transmit location data and cannot be tracked. If you want real-time location tracking, you need a separate GPS collar or device. A microchip works only when someone scans it in person.

Can a microchip hurt my pet or cause health problems?

Microchips are biocompatible and designed to remain safely under the skin for the pet's entire life. Serious complications are rare. Some pets may experience minor swelling or bruising at the implant site, which typically resolves within a few days. Discuss any concerns with your veterinarian before or after implantation.

What if my pet's microchip stops working?

Microchips do not have batteries and do not stop working. However, if a scanner cannot read your pet's chip, it may be because the chip has shifted position under the skin, the scanner is not compatible with that chip brand, or the scanner needs new batteries. If a shelter cannot read your pet's chip, ask them to try a universal scanner or contact the microchip company for troubleshooting.

Can I microchip my pet myself at home?

No. Microchips must be implanted by a licensed veterinarian or trained veterinary technician. Attempting to implant a microchip at home risks infection, improper placement, and injury to your pet. Always have the procedure done at a veterinary clinic or during a professional microchipping event.

What happens if I move and forget to update my microchip information?

If your pet is found and brought to a shelter, the staff will scan the chip, contact the microchip company, and retrieve your old address and phone number. They may send a letter to your previous address or call an old phone number that no longer works. Your pet may spend days or weeks in the shelter while staff try to locate you. Always update your microchip registration within a few days of moving.