Microchip

The ISO 11784/11785 standard

International standards ISO 11784 and 11785 define the 15-digit numeric structure and 134.2 kHz radio frequency that almost all veterinary and shelter scanners worldwide can read. Avoid older 125 kHz or 128 kHz chips that pre-date the standard; their numbers may not be readable by international scanners and can complicate travel.

The step owners skip, registration

An implanted chip without a current registration is a useless number. The chip itself contains no contact information, it points to a database entry that the owner is responsible for keeping current. Studies of shelter intake consistently find that the majority of microchipped lost pets cannot be returned because the registry record is missing, outdated, or links to a defunct phone number.

• Register the chip the day it is implanted, not 'later'.
• Update the registry when you move or change phone number.
• Maintain a secondary contact in the registry.
• In the US, AAHA's free Universal Pet Microchip Lookup tool reports which registry holds your chip number, use it to verify your record annually.

Safety and what microchips are not

Implantation is comparable to a vaccination, a single injection, typically without anesthesia. Adverse events (migration, local reaction, very rarely tumor formation) are documented but extremely rare relative to implantation volume. A microchip is not a GPS, it is passive RFID, readable only by a scanner held within a few centimeters. For real-time location tracking, a separate GPS collar device is required.

Why it matters

Microchipping is the single most effective intervention for getting a lost pet home, but only if the registration is current. We have watched 'microchipped' animals stay in shelters for weeks because the phone number in the registry was a decade old. Take five minutes to verify your record this year.