Microchipping: Identifying Horses

Microchipping is widely accepted as a safe, effective and tamper-proof method of identifying horses. It has been a requirement since 1999 for all Thoroughbred horses which are to be registered with Weatherbys for racing purposes to be microchipped.

Site and preparation for microchipping

The standard site for implantation is by deep injection into the nuchal ligament 2-3cm below the top of the left mid crest. Microchipping is considered an act of veterinary surgery and as such can only be carried by Veterinary Surgeons or qualified Veterinary Nurses under veterinary supervision.

Experience with microchipping a large number of horses has shown that adverse reactions are very rare. The skin at the site of implantation should be clean. At present there is no evidence to indicate that clipping and surgically preparing the site significantly reduces the risk of adverse reactions.

Adequate restraint of the animal is essential. In the case of foals, the animal should be restrained from the right-hand side, with one attendant at the head, and another at the tail. This allows the Veterinary Surgeon free access to the left side of the neck. Equally in older animals, adequate restraint is necessary and sedation should be used where necessary.

Technique for insertion

The site should be checked prior to implantation to ensure that the animal is not already microchipped. The microchip should then be tested before implantation and then again immediately after implantation to confirm successful placement. The Veterinary Surgeon must ensure that the type of scanner used is appropriate for use in horses.

The technique for implantation is as for any deep intramuscular injection. The implantation needle is inserted firmly to its full depth at an angle to the skin. The plunger is then fully depressed, held depressed and the needle withdrawn slowly. This and the angle of insertion minimizes the possibility of the microchip accidentally being withdrawn with the implanting device. It is not uncommon for the site to bleed. This is readily stemmed by pressure over the site for a few minutes.

Occasionally, microchips will migrate away from the left side of the mid crest following implantation. In these instances the eventual resting site for the microchip should be located and recorded on the silhouette using the symbol M to aid future identification of the horse.