Dr. Dawn Ruben
General Practice & Preventative Medicine


Microchips are fast becoming a popular method for permanent identification of pets. The chips are considered reliable and an effective way to identify lost pets. The chip is small, compact and easily inserted under the skin. But once inserted, there are two other equally important components of the microchip system that must be in place in order to properly identify and return lost pets to their owners; the microchip scanner and an accessible and accurate database. However, there is controversy regarding the chips and scanners.

The Controversy

AVID® and Home Again® microchips read on a frequency of 125 khz and have been commonly used in veterinary hospitals and shelters across the United States. Each company has universal scanners that can identify chips from each other as well as other microchip companies that create chips that are also 125 khz. Controversy involving microchips exists because one company (Banfield®) introduced a chip that was 134.2 khz and incompatible with other readers. Therefore, pets chipped with Banfield® microchips could not be identified with the most common microchip scanners on the market in the U.S. Banfield has since stopped selling the undetectable microchips in their clinics.


The microchip is a tiny computer chip or transponder about the size of a grain of rice. It stores an identification number and transmits that information through radio waves to the appropriate scanner. Typically, the microchip number contains 10 characters, making available 275 billion separate codes. This makes it highly unlikely that the same identifying code will be used more than once. Rest assured that your pet will have a unique microchip code.

Microchips are composed of a silicon chip and tiny antenna encased in biocompatible glass. The microchips come pre-loaded in a syringe, and the needle is inserted just under the skin between the shoulder blades where the microchip is implanted. The entire procedure takes less than 10 seconds and is only as painful as a vaccination injection.
After injection, the tissue surrounding the microchip reacts to this new substance and forms a casing. This helps prevent migration of the microchip. Since the microchip is made of biocompatible material, rejection is uncommon and infection at the site is very rare.


The microchip scanner is used as a power source for the microchip and is used to receive the message encoded in the chip. The scanner uses electromagnetic energy to empower the chip to transmit its message through radio waves, which are normally at specific frequencies for each manufacturer of microchips. For this reason, in the past, not all scanners could read all brands of microchips.

In an effort to address this potential problem, in 1996, the International Standards Organization published that universal readers must be produced. Scanners are provided to animal control, humane shelters and other rescue organizations in an effort to ensure that every stray pet is scanned and those with chips are reunited with their owners. Veterinarians can also purchase scanners for use in their hospital.


Even if your pet has a microchip and is properly scanned, without an accessible database, this information will not return your pet to you. When contacted with the identification code of a missing pet, the database personnel can retrieve the pet’s information. Each microchip that is sold is registered to the veterinary hospital or shelter that purchased it. It is the responsibility of the veterinary hospital to record your pet’s unique microchip identification number in his record and notify the microchip database.

In addition, you can register your pet in your own name for faster notification when your lost pet has been found. There is a charge for this service. These microchip databases are usually available 24 hours a day and are even accessible via the Internet. But remember, the database, as with computers, is only as good as the data it contains. Annual confirmation of your pet’s microchip information is strongly recommended.


In the United States, there are currently two active suppliers of microchips. American Veterinary Identification Devices (AVID®) and HomeAgain®. Each has unique codes and each support their own databases. Each is readily accessible.


To date, AVID® has sold several million microchips. According to a spokesperson, a pet is reunited with his owner every 32 minutes. Currently, over 142, 000 lost pets have been returned home. For more information on AVID® microchips, visit them at www.avidid.com or call 1-800-336-AVID.


To date, HomeAgain® has sold over 500,000 microchips and over 34,000 pets have been reunited with their owners. For more information on HomeAgain® microchips, visit them at http://www.homeagainid.com/ or call the HomeAgain Pet Recovery Service at 1-866-PET-ID24 (1-866-738-4324).


Your pet escapes the yard and is found a few miles away by an animal control officer, who takes the pet back to the shelter and scans the pet in hopes of finding a microchip code. When a code is found and displayed on the scanner, the shelter employee is able to determine which database to contact for further information. Once the database is contacted, the microchip code is given.

At this point, there are two outcomes. If the owner did not register his name and telephone number with the database, the veterinary clinic that purchased the microchip is listed. Unfortunately, the pet must stay at the shelter until the veterinary clinic can be contacted, usually the next business day, in order to determine the name and telephone number of the owner.

The other potential outcome is based on owner’s paying an additional fee and registering his name, address and telephone number, including alternates, with the database. In this situation, the database is able to supply your telephone number to the shelter employee. The shelter can then contact you directly, resulting in reuniting you with your pet that night.


· It is recommended that all pets are microchipped. Even those pets that do not venture outside may escape one day.

· Register your pet!!! It is recommended that you pay the additional fee and have your name and telephone number listed with the microchip code.

· It is recommended that you use an identifier on your pets collar indicating that he or she has a microchip and what kind.

· An annual visit to the veterinarian specifically to test the microchip is recommended. Have your veterinarian scan your pet to determine if the chip is still transmitting data.

· Annually confirm your pet’s information with the microchip database and ensure that all contact information including your address, home and cell phone numbers, email address, and pager number, etc are all current.