External identification

Forms of external identification include collar tags with identifying information numbers or QR codes with the pet information or pet recovery service organization information. The pet could be tracked through a service toll-free number or web address on the tag; the service accesses the pet and owner information in a database via a number or QR code. Some pet identification tags include the owner's address or phone number which can be used to reunite the pet with its owner. There are also registry database services based on tattoo registries.

Electronic tracking devices

Collar-attached electronic tracking devices are used by recovery service providers to reunite the pet with its owner. The contract may also include recovery services, which eliminates any need to rely on the pet encountering a helpful stranger. However, at least one device also call for help from anyone nearby. This depends on whether the device is GPS, radio, or Bluetooth.^[4]

Example of an RFID (radio-frequency identification) scanner used with animal microchip implants.

Microchip implant

Since the early 1990s, the underskin I.D. tag or microchip implant has been promoted as a solution for pet recovery that does not require a collar. Veterinary services, animal shelters, and even some individuals have a chip scanner. In the U.S. such services are unregulated, and several types of chips have emerged with only some adhering to the pertinent ISO standards, ISO 11784 and ISO 11785. Originally each type had its scanner with no ability to read or even detect other types but there is now a move toward universal scanners able to read all types. But unlike the identifying collar tags mentioned above, the appropriate database keeper cannot always be determined from the ID number, complicating the task of returning the pet to its owner.^[5]

Metasearch engines

As an aid to the pet finder in this situation, chip registry metasearch engines have been established. Two that have been available at least since 2003 are Europetnet, which has a large number of participating European registries, and Petmaxx, a worldwide registry service. In 2009, the metasearch engine, sponsored by the American Animal Hospital Association,^[6] was put online. Most of the major U.S. registries are now participants.

Pets are reunited with their owners by the stray pet's code whose information is accessed via a database. The services are only accessed where chip registry services have decided to interface with metasearch engine services.

Successful metasearch engines connect to all the available registries and can help the pet finder or dog warden find the one registry that has an owner record for a found stray. A potential downfall is that if the pet's information is not registered with all databases, a thief can steal the animal using the 'secure and tamper-proof' ID device, register the stolen pet with another database, and then sell the animal on, transferring apparent clear title in the form of a login account at, or registration document from, the second registry.

A drawback with metasearch engines is that many shelters do not have the manpower to search registry sites for owner information once they access the chip number. The chip number may simply be entered in the paperwork, never contacting the owner.

Microchip Registration Database

To ensure lost pets are reunited with their owner it is best to have them microchipped and to register them with the chip manufacturer and/or one of the chip-agnostic recovery Pet recovery services. An implantable chip is more secure than a collar tag because the chip cannot be moved between pets or lost as can a collar tag. A typical pet microchip registration costs $25 to $100 per year and it is incumbent upon the owner to maintain the accuracy of the database in the event of a move or change in contact information. To remind pet owners to check and update their information, the American Animal Hospital Association and the American Veterinary Medical Association have established August 15 as Check a Chip Day.^[7] Registering and keeping the owner's contact information up to date is the most problematic problem facing the pet microchip industry because without up-to-date information a lost pet is less likely to be returned to its owner. According to an Ohio State University study, the main reasons owners aren't found for lost pets included incorrect or disconnected phone numbers (35.4%), owner's failure to return phone calls or respond to letters (24.3%), unregistered microchips (9.8%) or microchips registered in a database that differed from the manufacturer (17.2%).^[8] At a mostly yearly, subscription cost to the owner, each microchip manufacturer maintains their registration database. However, these registration databases only hold information related to chips they manufacture requiring a pet finder that does not know who the manufacturer is to search multiple sources to report a found pet.  There are free registration databases available such as those at Veripet's Rabies Reader page and Found Animals are chip manufacture agnostic.

A recovery database of last resort at the American Animal Hospital Association (AAHA) provides a lookup tool (see External Links below) that will redirect a user to the manufacturer's recovery desk but not supply owner information or notifications to them. AAHA works only with those manufacturers and recovery services that provide a hotline where a pet finder can report a found pet.