Pet Microchipping: Everything You Need to Know

Every year, approximately 10 million dogs and cats are lost in the United States. Of those, only about 15–20% of dogs and fewer than 2% of cats without microchips are ever reunited with their owners. Microchipping dramatically changes those odds. A landmark 2009 study published in the Journal of the American Veterinary Medical Association (JAMA) found that microchipped dogs were returned to their owners 52.2% of the time, compared to 21.9% for non-microchipped dogs. For cats, the difference was even more stark: 38.5% of microchipped cats were reunited with their families versus only 1.8% of those without chips.

Despite these compelling statistics, many pet owners remain uncertain about microchipping — how it works, whether it hurts, what it costs, and whether it is truly necessary. This guide provides a thorough, evidence-based overview of everything you need to know about pet microchipping.

How Pet Microchips Work

A pet microchip is a radio-frequency identification (RFID) transponder enclosed in a biocompatible glass capsule approximately the size of a grain of rice — typically 11–14 millimeters long and 2 millimeters in diameter. The chip contains a tiny integrated circuit and an antenna coil, but no battery or power source of its own. It is a completely passive device.

When a compatible scanner is passed over the area where the chip is implanted, the scanner emits a low-frequency radio signal that energizes the microchip’s antenna coil through electromagnetic induction. This energy activates the integrated circuit, which transmits its unique identification number back to the scanner. The entire exchange happens in milliseconds and requires no power from the chip itself. Because there is no battery, a microchip has no moving parts and nothing that wears out — it is designed to last the lifetime of the animal.

Frequency Standards

Historically, microchips in the United States operated at different frequencies, which created compatibility problems. Some chips operated at 125 kHz, others at 128 kHz, and internationally the standard was 134.2 kHz as defined by the International Organization for Standardization (ISO) standards 11784 and 11785. If a shelter had a scanner calibrated for 125 kHz chips, it might not detect a 134.2 kHz chip, and vice versa.

This issue has been largely resolved. The American Animal Hospital Association (AAHA) and the American Veterinary Medical Association (AVMA) recommend ISO-compliant 134.2 kHz chips, and most modern scanners are universal or “forward-reading” scanners capable of detecting chips at all common frequencies. However, some older scanners still in use at certain shelters or veterinary clinics may not read all chip types, which is why the AAHA Universal Pet Microchip Lookup tool is so valuable — it searches multiple registries simultaneously regardless of chip brand or frequency.

What Information Is on the Chip?

A critical point of misunderstanding: the microchip itself stores only a unique identification number, typically 9, 10, or 15 digits long. It does not contain your name, address, phone number, medical records, or any other personal information. The chip number is linked to your contact information in an external database maintained by the microchip manufacturer or a third-party registration service. When a veterinarian or shelter worker scans a found pet and retrieves the chip number, they must then look up that number in a registry to find the owner’s contact details.

This is why registration is absolutely essential. An unregistered microchip is essentially useless — it produces a number that leads nowhere. The JAMA study mentioned above found that the primary reason microchipped animals were not returned to their owners was that the chip was not registered in a database, or the registration information was out of date.

The Implantation Procedure

Microchip implantation is a quick, routine procedure that can be performed during a regular veterinary visit. No anesthesia or sedation is required, although many veterinarians choose to implant chips during spay/neuter surgery when the animal is already under anesthesia as a matter of convenience.

The chip is preloaded in a sterile, disposable applicator with a hypodermic needle. For dogs and cats, the standard implantation site is the subcutaneous tissue between the shoulder blades (the dorsal midline of the interscapular region). The veterinarian tents the skin, inserts the needle, depresses the plunger to deposit the chip, and withdraws the needle. The entire process takes only a few seconds.

The needle used for microchip implantation is larger than a standard vaccination needle — typically 12-gauge compared to the 22–25-gauge needles used for most injections. Most animals react similarly to how they would during a routine vaccination: a brief flinch or startle, followed by immediate return to normal behavior. Puppies and kittens may show slightly more reaction simply because they are smaller, but the procedure is well-tolerated across species and ages.

After implantation, the veterinarian will scan the chip to confirm it is reading correctly and that the number matches the paperwork. A thin layer of biocompatible material on the chip’s surface (often a polypropylene polymer shell coated with a material called Parylene C) encourages a mild tissue reaction that causes the surrounding tissue to form a thin capsule around the chip, anchoring it in place and preventing significant migration.

Microchipping Other Species

While dogs and cats are the most commonly microchipped pets, the technology is used across many species. Horses are routinely microchipped (typically in the nuchal ligament on the left side of the neck) for identification in competition, breeding, and travel. Birds, particularly parrots and other large psittacines, can be microchipped in the pectoral muscle. Reptiles, including turtles, tortoises, and larger lizards, are microchipped for identification, especially for species protected under CITES (Convention on International Trade in Endangered Species). Even ferrets, rabbits, and pot-bellied pigs can be microchipped. The implantation site and needle size may vary by species, but the underlying technology is the same.

Registration: The Most Critical Step

Implanting a microchip without registering it is like installing a lock on your front door and throwing away the key. The chip number must be associated with your current contact information in a searchable database for the system to work.

When your pet is microchipped, you will receive paperwork with the chip number and instructions for registration. Most microchip manufacturers maintain their own databases: HomeAgain, PetLink (by Datamars), the AKC Reunite database, and others. Registration typically costs $15–25 for a one-time or lifetime enrollment, though some companies charge annual fees for premium services like lost-pet alerts and 24/7 hotlines.

You can register your chip with the manufacturer’s database and, additionally, with free registries like the Found Animals Registry. The more databases your chip number appears in, the better the chances of being found in a lookup.

The AAHA Universal Pet Microchip Lookup tool (available at petmicrochiplookup.org) is an invaluable resource. Rather than requiring shelters to guess which manufacturer made a specific chip and check individual databases, this tool searches across participating registries simultaneously. Veterinary clinics, shelters, and animal control officers use it routinely when they scan a found animal.

Keeping Your Information Current

One of the most common failures in the microchip system is outdated registration information. If you move, change your phone number, or change your email address, you must update your microchip registration. Many people forget this step, especially during the chaos of a move — which is precisely when pets are most likely to become lost and disoriented.

Set a recurring annual reminder to verify your microchip registration. Most registries allow you to update your information online in minutes. Also confirm that your veterinarian scans your pet’s chip at each annual wellness visit to ensure it is still functioning and reading correctly.

Cost of Microchipping

Microchipping is one of the most affordable and effective investments you can make in your pet’s safety. At a full-service veterinary clinic, the typical cost ranges from $25 to $75, which includes the chip, implantation, and initial registration. Many animal shelters and rescue organizations include microchipping in their adoption fee or offer it at reduced cost — often $10–20 at community microchipping events.

Low-cost clinics and mobile vaccination events frequently offer microchipping for $15–25. Some municipalities and nonprofit organizations sponsor free microchipping events, particularly in underserved communities. Given that the chip lasts a lifetime and the cost of losing a pet — emotionally and financially — is immeasurable, microchipping offers extraordinary value.

Common Myths About Pet Microchips

Myth: Microchips Are GPS Trackers

This is perhaps the most widespread misconception. A microchip is not a GPS tracker. It cannot tell you where your pet is in real time. It has no battery, no transmitter, and no connection to satellites or cellular networks. It can only be read when a compatible scanner is held within a few inches of the implant site. If you want real-time location tracking for your pet, you need a separate GPS-enabled collar device, which requires battery charging and typically a monthly subscription fee. Microchips and GPS collars serve complementary but entirely different functions: GPS helps you find a lost pet actively, while a microchip provides permanent identification if someone else finds your pet.

Myth: Microchips Cause Cancer

This concern arose from a handful of laboratory studies in the early 2000s that found tumors developing around microchip implantation sites in certain strains of mice and rats. However, these were specific rodent strains bred to be genetically predisposed to tumor development (including foreign-body sarcomas), and the findings have not been replicated in dogs, cats, or other companion animals at any clinically meaningful rate.

The British Small Animal Veterinary Association (BSAVA) maintains a database tracking adverse reactions to microchips and has documented an adverse reaction rate of approximately 0.0003% across millions of implanted chips. The AVMA, AAHA, and World Small Animal Veterinary Association (WSAVA) all consider microchipping to be safe and recommend it for all companion animals. The overwhelming benefit of identification and recovery far outweighs the infinitesimally small risk of adverse reaction.

Myth: Microchips Migrate Throughout the Body

Minor migration of the chip from the original implantation site can occur, particularly in the weeks following implantation before the tissue capsule fully forms. A chip implanted between the shoulder blades might shift slightly toward one shoulder or down the back. Significant migration is rare, and when it does occur, it does not pose a health risk to the animal. This is why scanning protocols call for sweeping the entire body — not just the interscapular region — when checking for a microchip. Modern chips with anti-migration coatings have further reduced the incidence of significant movement.

Myth: Collars and Tags Are Sufficient

Collars and ID tags are an important first line of identification — they allow anyone who finds your pet to contact you immediately without needing a scanner. However, collars can break, slip off, or be removed. Tags can become illegible over time. A microchip is a permanent, tamper-proof form of identification that cannot be lost, removed, or damaged under normal circumstances. The best approach is to use both: a collar with visible ID tags for immediate identification and a registered microchip as a permanent backup.

Legal Requirements and International Travel

Microchipping requirements vary by jurisdiction. In the United States, several states and many municipalities have enacted mandatory microchipping laws, typically requiring that all dogs (and sometimes cats) adopted from shelters or purchased from breeders be microchipped. Check your local ordinances for specific requirements.

For international travel, microchipping is almost universally required. The European Union, United Kingdom, Australia, Japan, and most other countries require an ISO 11784/11785 compliant 15-digit microchip for pet entry. Many countries require that the microchip be implanted before the rabies vaccination so that the vaccination record is linked to a verifiable identification number. If your pet has a non-ISO chip (such as an older 9- or 10-digit chip common in the US), some countries will not accept it, and you may need to have an ISO-compliant chip implanted in addition to the existing one, or bring a compatible scanner with you.

The USDA Animal and Plant Health Inspection Service (APHIS) oversees international pet travel health certificates for the United States. If you plan to travel internationally with your pet, begin the process well in advance — some countries require blood titer tests, waiting periods of up to six months, and specific documentation timelines that all hinge on the pet being microchipped first.

What to Do If Your Pet Is Lost

If your microchipped pet goes missing, take these immediate steps: contact the microchip registry to report the pet as lost (most registries have online lost-pet reporting features and will flag the chip number); notify local animal shelters and animal control agencies, providing the microchip number; file a lost-pet report with local police; post on social media and community boards; and physically search your neighborhood. If someone finds your pet and takes it to any veterinary clinic or shelter, the chip will be scanned and the registry contacted. The faster you report the loss and the more current your registration information is, the faster the reunion can happen.

A Lifelong Investment in Safety

Microchipping is endorsed by the AVMA, AAHA, WSAVA, and virtually every major veterinary and animal welfare organization worldwide. It is quick, safe, affordable, and permanent. Combined with a registered database entry that you keep current, a microchip provides your pet with the best possible chance of being returned to you if they ever become separated from your care. Whether you have a dog, cat, bird, rabbit, reptile, horse, or ferret, microchipping is one of the simplest and most impactful steps you can take as a responsible pet owner.

Disclaimer: This article is for educational purposes only and does not constitute veterinary advice. Always consult with a qualified veterinarian for specific health concerns about your pet. See our Medical Disclaimer for complete details.

Last updated: March 2026 · Editorial Standards