Equine Microchips

What are equine microchips?

A microchip is an integrated electronic circuit that uses radio-frequency identification (RFID) technology. Each microchip has a unique number, which cannot be altered or deleted, that can be read by a hand-held radio frequency scanner. The chip reader emits radio waves at a frequency of 134.2 kilohertz (kHz) (international standard) or 125 kHz (national standard) that stimulate the chip to respond back to the reader with the unique identification information. In the early days of animal microchipping, chip and reader compatibility was an issue. However, today’s global standards have negated this incompatibility. A universal scanner can read any International Standard Organization (ISO) microchip regardless of the manufacturer.

Microchips are small (about the size of a grain of rice), safe, inexpensive forms of permanent identification for animals. They are an asset for reuniting animals with their owners after theft, natural disasters, and accidents, as well as for monitoring animal movement, tracing animals during disease outbreaks, and preventing fraud at competitions. Microchips generally last for the life of the animal.

How and where are equine microchips implanted?

In horses, microchips are usually implanted with a needle and syringe in the nuchal ligament, halfway between the poll and withers, on the left side of the neck. Recent studies have evaluated implanting microchips into muscle as well. Anesthesia is not required for microchip implantation, but it is a veterinary procedure and should be performed, or at least supervised, by a licensed veterinarian. Microchips generally do not migrate after implantation in horses (Stein et al. 2003; Gerber et al. 2012). Horses may exhibit a local inflammatory response characterized by swelling and sensitivity to pressure at the insertion site that usually resolves in one to three days (Gerber et al. 2012).

Does my horse have to be microchipped?

Various breed registries and discipline-specific organizations, including the Federation Equestre Internationale (FEI), United States Equestrian Federation (USEF; for USHJA-registered horses), Jockey Club, and US Trotting Association, require horses to be microchipped in order to compete, earn points, or win prize money. Rules and regulations generally specify that microchips must be ISO 11784 and 11785 compatible.

ISO 1174 is the International Standard that specifies the radio-frequency (RF) identification code’s structure. For horses, this is a 15-digit number. ISO 11785 is the International Standard that identifies the specific characteristics of the transmission protocols between the transponder and the transceiver.

Advanced Technologies

In addition to microchips that store unique ID numbers, newer chips include those that have built-in temperature sensing technology. These biothermal chips provide quick, non-invasive temperature monitoring. Microchips under development include those that can store health data such as vaccination records and Coggins test results.

Microchip Mythbusters

• Microchips cannot be inactivated with a magnet.
• Microchips do not migrate from the implantation site.
• Microchips do not cause cancer.
• Microchips do not contain GPS.

Additional resources

American Association of Equine Practitioners (AAEP) Position on Microchips for the Identification of Equids

Chip Your Horse, AAEP

American Horse Council Microchip Look-Up

Equine Microchip Lookup

AQHA Microchip Pilot Project

International Committee for Animal Recording (ICAR)

Gerber, M.I., Swinker, A.M., Staniar, W.B., Werner, J.R., Jedrzejewski, E.A., Macrina, A.L. 2012. Health Factors Associated with Microchip Insertion in Horses. J Eq Vet Sci 32(3):177-182.

Stein, F.J., Geller, S.C., Carter, J.C. 2003. Evaluation of microchip migration in horses, donkeys, and mules. J Am Vet Med Assoc 223(9):1316-9.