You, Your Vet, and the National Animal Identification System

Recently, horse owners have been hearing a lot about animal identification and microchipping. As many already know, the USDA has, for the past four years, been developing and implementing the voluntary National Animal Identification System (NAIS) in order to rapidly trace an animal disease to its source (the goal is 48-hour traceback). Only production livestock and some horses are included in the focus of this system. Those horses that move frequently off their main premises (base farm or stable) and are commingled with horses from other locations are of primary interest due to the greater potential of disease spread.

The NAIS consists of three phases: Premises registration, animal identification, and tracing. Each is voluntary at the federal level. Many boarding facilities and stables already have premises registration numbers. In late 2007 the second phase for horse owners, an NAIS-compliant injectable transponder (microchip), was approved by the USDA. The injectable transponder utilizes radiofrequency (RF) technology and is encoded with the NAIS animal ID code. This code, referred to as the Animal Identification Number (AIN), is a national numbering standard for the identification of individual animals. Such standards with the incorporation of RF technology will support animal health programs and all other activities associated with the equine industry, including domestic and international movement of horses.

Requirements for the NAIS-compliant transponder follow the recommendation of the Equine Species Working Group, including the International Organization of Standards (ISO) 11784 and 11785 for radiofrequency identification. The transponder, when read, gives the AIN, a unique 15-digit number starting with 840. The number, 840, is the country code for the United States. The remaining digits provide the unique identification code for each horse. Only ISO-compliant transponders, which are manufactured by Destron Fearing, are NAIS-compliant, but horses previously implanted with other transponders, including the 125 kHz microchips, will be grandfathered into NAIS. The NAIS- compliant transponders were made available early this year through AIN device managers.

If a veterinarian chooses to be an AIN device manager, he or she will be responsible for reporting the AIN encoded in the transponder to the AIN management system maintained by USDA. Some breed registries may also choose to distribute the chips to premises as part of the foal registration process. In this event, the breed registry that provides the AIN device to a breeder's premises will be responsible for reporting the AIN distribution record. Before the AIN injectable transponders can be obtained and implanted, the premises where the horse is located must have a premises identification number. The premises number can be obtained by filling out a simple form available from the state veterinarian's office or from the department of agriculture in the state where the premises is located. Information is also available by going to

While NAIS is a voluntary program, the use of the premises identification number and the animal identification number on Certificates of Veterinary Inspection (CVI) and EIA (Coggins) tests will greatly enhance the ability to trace horses timely when there is a disease of concern.

As we have seen recently with equine influenza in Australia and equine herpesvirus myeloencephalopathy (EHM, also known as neurologic EHV-1) in the United States, an animal disease outbreak can restrict horse movements, sales, shows, and commerce. The NAIS is the best and most modern way to quickly control and limit the spread of a disease. So far, over 430,000 premises in the United States have been registered, and many premises owners are choosing to participate in the animal identification component of NAIS. Additional information about what NAIS offers horse owners can be obtained by going to or by visiting the NAIS Web site. Registering your premises is fast and easy. We encourage you to get the facts and make the decision to sign up today.

By Tim Cordes, DVM, senior staff veterinarian for Equine Programs and national coordinator for Equine Diseases in the USDA's Animal and Plant Health Inspection Service Veterinary Services; and Neil E. Hammerschmidt, the Veterinary Services programs NAIS coordinator and staff liaison to the Equine Species Working Group.

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