San Juan Veterinary Hospital

2197 E Hwy 160
Pagosa Springs, CO 81147


A microchip implant is an identifying integrated circuit placed under the skin of a dog, or cat, or other animal. The chips are about the size of a large grain of rice and are based on a passive RFID technology. 
Uses and benefits
Microchips have been particularly useful in the return of lost pets. They can also assist where the ownership of an animal is in dispute.
Animal shelters and animal control centers benefit using microchip identification products by more quickly and efficiently returning pets to their owners. When a pet can be quickly matched to its owner, the shelter avoids the expense of housing, feeding, providing medical care, and outplacing or euthanizing the pet. Microchipping is becoming increasingly standard at shelters: many require all outplaced animals to receive a microchip, and provide the service as part of the adoption package.
In addition to shelters and veterinarians, microchips are used by kennels, breeders, brokers, trainers, registries, rescue groups, humane societies, clinics, farms, stables, animal clubs and associations, researchers and pet stores. Animal control officers are also trained and equipped to scan animals.
Several countries require a microchip when importing an animal, as a proof that the animal and the vaccination record belong together.
System of recovery
Effective pet identification and recovery depends on the following:
  • A pet owner either adopts a pet at a shelter that microchips some or all adoptee animals, or the owner with an existing pet brings it to a veterinarian (or a shelter) that provides the service.
  • The shelter or veterinarian selects a microchip from their stock, makes a note of that chip’s unique ID, and then inserts the chip into the animal with a syringe. The injection requires no anesthetic.
  • Before sending the animal home, the vet or shelter performs a test scan on the animal. This helps ensure that the chip will be picked up by a scanner, and that its unique identifying number will be read correctly.
  • An enrollment form is completed with chip number, the pet owner’s contact information, the name and description of the pet, the shelter’s and/or veterinarian’s contact information, and an alternate emergency contact designated by the pet owner. (Some shelters or vets, however, choose to designate themselves as the primary contact, and take the responsibility of contacting the owner directly. This allows them to be kept informed about possible problems with the animals they place.) The form is then sent to a registry keeper to be entered into its database. Depending on regional custom, selected chip brand, and the pet owner’s preference, this registry keeper might be the chip’s manufacturer or distributor, or an independent provider. In some countries a single official national database may be used. The registry keeper typically provides a 24-hour, toll-free telephone service for pet recovery, good for the life of the pet.
  • The pet owner is also provided the chip ID and the contact information of the recovery service. This is often in the form of a collar tag imprinted with the chip ID and the recovery service’s toll-free number, to be worn by the animal.
  • If the pet is lost or stolen, and is found by local authorities or taken to a shelter, it is scanned during intake to see if a chip exists. If one is detected, authorities call the recovery service and provide them the ID number, the pet’s description, and the location of the animal. If the pet is wearing the collar tag, anyone who finds the pet can call the toll-free number, making it unnecessary to involve the authorities. (The owner can also preemptively notify the recovery service directly if a pet disappears. This is useful if the pet is stolen, and is taken to a vet who sans it and checks with the recovery service.)
  • The recovery service notifies the owner that the pet has been found, and where to go to recover the animal.
Many veterinarians perform test scans on microchipped animals every time the animal is brought in for care. This ensures the chip still performs properly. Vets sometimes use the ID as the pet’s ID in their databases, and print this number on all outgoing paperwork associated with its services, such as receipts, test results, vaccination certifications, and descriptions of medical or surgical procedures.
Components of a microchip
Microchips are passive, or inert, RFID devices and contain no internal power source. They are designed so that they do not act until acted upon.
Three basic elements comprise most microchips: A silicon chip (integrated circuit); a coil inductor, or a core of ferrite wrapped in copper wire; and a capacitor. The silicon chip contains the identification number, plus electronic circuits to relay that information to the scanner. The inductor acts as a radio antenna, ready to receive electrical power from the scanner. The capacitor and inductor act as a tuner, forming an LC circuit. The scanner presents an inductive field that excites the coil and charges the capacitor, which in turn energizes and powers the IC. The IC then transmits the data via the coil to the scanner.
These components are encased in a special biocompatible glass made from soda lime, and hermetically sealed to prevent any moisture or fluid entering the unit. Barring rare complications, dogs and cats are not affected physically or behaviorally by the presence of a chip in their bodies.
Implant Location
In dogs and cats, chips are usually inserted below the skin at the back of the neck, between the shoulder blades on the dorsal midline. The chip can often be manually detected by the owner by gently feeling the skin in that area. It stays in place as thin layers of connective tissue form around the biocompatible glass which encases it.
Horses are microchipped on the left side of the neck, half the distance between the poll and withers, and approximately one inch below the midline of the mane, into the nuchal ligament.