Learn About Pet Microchip Options and Information

Understanding Pet Microchips: What They Are and How They Work

A pet microchip is a small electronic device, about the size of a grain of rice, that contains identification information about your pet. The chip itself is a passive RFID (radio frequency identification) tag, meaning it does not have a battery and does not transmit signals on its own. Instead, when a veterinarian or animal shelter scans your pet with a handheld microchip reader, the reader emits a radio frequency that activates the chip temporarily. The chip then sends back the unique identification number stored within it.

The microchip is typically inserted under the skin of your pet, usually between the shoulder blades. The insertion process takes only seconds and is similar to receiving a vaccination. Most veterinarians report that pets experience minimal discomfort during the procedure. The chip remains in place for the life of your pet and requires no batteries, maintenance, or replacement unless it becomes damaged—which is rare.

According to the American Veterinary Medical Association (AVMA), approximately 42% of shelters and veterinary clinics can read microchips. However, this number varies by region and facility type. The microchip itself does not contain GPS or tracking capabilities, despite common misconceptions. It is purely an identification tool that works when scanned at close range, typically within a few inches to a foot away.

Microchips operate on different frequencies depending on the manufacturer and region. The most common frequencies in North America are 125 kilohertz (kHz) and 128 kHz for older chips, while newer microchips often use 134.2 kHz, which is the international standard. Some newer scanners are "universal" and can read multiple frequencies, but older scanners may only read specific frequencies. This frequency variation is an important consideration when choosing a microchip.

The actual microchip contains no personal information—it only holds a unique identification number. When a scanner reads this number, that number must be cross-referenced with a microchip registry database to retrieve your contact information and your pet's details. This two-step process (scanning for the number, then looking up the number in a registry) is how shelters and veterinarians reconnect lost pets with their owners.

Practical Takeaway: Microchips are reliable, long-lasting identification tools that work passively without batteries or GPS. Understanding that the chip itself holds only a number—not your contact information—helps explain why registering your pet with a microchip registry is just as important as the physical chip itself.

Different Types of Microchips Available on the Market

Several manufacturers produce microchips for pets, and each offers slightly different features and operates at different frequencies. The three largest microchip manufacturers in North America are HomeAgain (owned by Merck), AKC Reunite (owned by the American Kennel Club), and 24PetWatch. Each of these companies maintains its own registry database, though many veterinarians and shelters use scanners that can read multiple chip types.

HomeAgain microchips use the 134.2 kHz frequency and are sold under various brand names by different veterinary distributors. HomeAgain offers a registry service that includes lost pet alerts through social media and email notifications to shelters within a designated radius. The company also provides lost pet recovery services and maintains a database of approximately 10 million registered pets. HomeAgain chips are implanted by veterinarians during a routine office visit.

AKC Reunite microchips also operate at 134.2 kHz and are associated with one of the oldest pet recovery registries in the United States, established in 1985. AKC Reunite offers a lifetime registration option with no recurring fees after the initial registration. This registry maintains records for over 8 million pets. AKC Reunite also provides services for international pet recovery, which may be relevant if you travel across borders with your pet.

24PetWatch operates microchips at both 125 kHz and 134.2 kHz frequencies, offering options for different regional preferences. This company maintains a database and provides optional recovery services that include telephone support and social media alerts. 24PetWatch also offers optional pet health records storage as part of their registry service, allowing veterinarians to access medical history during emergency situations.

Some regional and international microchip manufacturers exist, particularly outside North America. European microchips typically use the 134.2 kHz frequency to comply with international standards. If you plan to travel internationally with your pet or adopt a pet from another country, understanding the microchip frequency and which registries operate in your destination area is important.

Older microchips, implanted before approximately 2010, may operate at 125 kHz or other frequencies. This older standard is still in use but is increasingly being phased out. The challenge with older chips is that not all modern scanners can read them. Some veterinarians and shelters maintain older scanners specifically to read these legacy chips, but coverage is inconsistent.

Practical Takeaway: Different microchip manufacturers operate at different frequencies and maintain separate registries. When selecting a microchip, research which registries operate in your area and whether your preferred veterinarian stocks that particular brand.

The Microchip Registration Process and Database Systems

Implanting a microchip is only the first step. The microchip cannot help reunite you with your pet unless the identification number is registered in a database along with your contact information. Unfortunately, studies indicate that many microchips are implanted but never registered. The AVMA estimates that approximately 25% of microchipped pets are never registered in any database.

When you have a microchip implanted at a veterinary clinic, the veterinarian typically provides you with registration paperwork that includes the microchip's unique identification number. You are responsible for completing this registration with the appropriate registry database. Some veterinarians offer to register the chip for you as part of the service, but this should be confirmed in writing. Even when a veterinarian registers the chip, you should verify that the registration is complete and contains your correct contact information.

Each microchip registry operates independently, maintaining its own database. HomeAgain, AKC Reunite, 24PetWatch, and other registries do not automatically share information with each other. This means that if a shelter scans a chip and finds it is registered with HomeAgain, they will look up your information in the HomeAgain database. If your information is not current in that specific database, the registry cannot contact you, even if the chip is registered elsewhere.

To register your microchip, you typically visit the registry's website, provide your pet's information (name, species, breed, color, date of birth), your contact information (name, address, phone number, email), and your veterinarian's information. Most registries charge a one-time registration fee ranging from $15 to $30, though some offer lifetime registration at higher initial cost. Some registries offer free registration as an incentive for implanting their brand of chip.

After initial registration, it is your responsibility to update your information if you move, change phone numbers, or change email addresses. Studies show that many reunions fail because shelters cannot contact pet owners because their registry information is outdated. It is recommended that you update your registry information any time your contact details change, and to check your registration information annually to verify accuracy.

Some microchip registries now participate in partnerships with other databases. For example, HomeAgain maintains partnerships with certain shelter systems and veterinary software programs, allowing shelters to access multiple registries from a single scanning system. However, universal access across all registries is not yet standard practice.

Practical Takeaway: Registering your microchip is as critical as having it implanted. Verify that your information is in the correct registry database and commit to updating it any time your contact information changes.

Comparing Microchip Options: Cost, Features, and Registry Services

The cost of microchipping varies depending on where you have the procedure performed and which microchip brand is used. At a standard veterinary clinic, microchipping typically costs between $25 and $60 for the implantation alone. Some clinics include the initial registry registration fee in this cost, while others charge separately. Low-cost spay and neuter clinics often offer microchipping at reduced rates, sometimes as low as $15 to $25.

Animal shelters and rescue organizations frequently offer microchipping services at