Although the number of dogs euthanized in shelters is a small fraction of the estimates that have been bandied about for years, there are still too many healthy dogs dying because their owners can't find them and too many owners heartbroken at the loss of their pets. There are also lots of stray dogs that wind up in rescues, no-kill shelters, and with new owners because the original owner cannot be located.
Statewide dog license laws are supposed to help return lost dogs to their owners, but they don't work very well. Few people obey the law, and many dogs lose their collars and tags somewhere between the yard they escaped from and the truck that carts them to the shelter.
Owners of purebred show and breeding dogs have long used tattoos to comply with the rules of identification of the American Kennel Club and to provide permanent, visible identification should their dogs get lost. Many pet owners also tattoo their dogs to prevent loss. But tattoos have a drawback as well; although they cannot get separated from the dog as tags can, they can be hard to find and read if the dog is frightened, aggressive or has a heavy haircoat, so few shelters make the effort.
Enter the microchip, a tiny transponder the size of a grain of uncooked rice. This is a permanent radio-frequency identification (RFID) chip implanted under the dog's skin and read by a chip scanner or wand. Implantation is done with an injector that places the chip under the loose skin over the dog's shoulder.
The advantages are obvious the process is quick and no more painful than a vaccination, the chip can't get lost, the number is unique, the dog doesn't have to be wrestled to the ground and shaved to see if it's there, and the owners name and address are available on regional or national data bases so a dog can be returned quickly and safely.
The chip identification number is stored in a tiny transponder that can be read through the dog's skin by a scanner emitting low-frequency radio waves. The frequency is picked up by a tiny antenna in the transponder, and the number is retrieved, decoded, and displayed in the scanner readout window. The radio waves use a frequency much lower than AM broadcast stations use, and they must be approved by the Federal Communications Commission before they can be marketed.
The chip, antenna, and capacitor are encased in a tiny glass tube. The tube is composed of soda lime glass, which is known for compatibility with living tissue. The glass is hermetically sealed to keep moisture out.
Two companies, Schering-Plough Animal Health and AVID, share the bulk of the business of pet identification by microchip.
In 1996, Schering-Plough Animal Health, marketer of the HomeAgain microchip identification system, announced distribution of a universal scanner by Destron-Fearing* that can read all microchips and removed a major obstacle to widespread acceptance of pet identification with the new technology. Until then, no one scanner could read the chips of all the US manufacturers, a situation that impeded efforts to involve shelters in a national effort to return stray dogs to their owners through a chip program. The new scanners were given to thousands of shelters throughout the country so that quick and easy identification of those dogs with microchips could be achieved.
There are some drawbacks. AVID® encoded its chips so that the number cannot be read, even by the HomeAgain universal scanner. Unless the shelter has an AVID® scanner, the best it can do is identify that a chip from AVID® is present. Thus it is still necessary to have access to at least two scanners in order to assure that the chip number can be retrieved.
A few chips do move out of place and can't be found by the scanner, a problem that Schering-Plough's Destron system addressed with a polypropylene shell on the tip of its transponder. This coating bonds the transponder to the dog's subcutaneous tissue.
Dogs can be scanned when picked up by an animal control officer or brought to the shelter. If a chip is present, the scanner will read the number and the shelter staff member can call the appropriate registry for the identity of the owner.
As a double protection for dogs chipped with HomeAgain, veterinarians who install the chips have scanners. Thus a found pet can be taken to a veterinary clinic for scanning and may never make the trip to a shelter.
Until February 2005, the American Kennel Club Companion Animal Recovery affiliate served as the registry for the Schering-Plough HomeAgain system and accepted enrollments from other systems as well. At that time, Schering-Plough set up its own registration/recovery database. However, AKC/CAR continues to enroll microchipped animals from any system for $12.50.
The chips used by HomeAgain and AVID® work on a frequency of 125 kHz. Banfield the Pet Hospital, a chain of animal health clinics at PetsMart stores, tried to get into the market by selling chips that work on a frequency of 134 kHz, the standard chip used to identify livestock, zoo animals, and wildlife throughout the world. Scanners that read the 125 kHz chips cannot read the 134 kHz version. A lawsuit from AVID® blocked Banfield from selling its chip.
However, since the 134 kHz chip is standard in 150 countries and the US is part of the International Standards Organization governing scientific standards, the US Congress is considering an addition to the 2005 Agriculture Budget Bill that directs the US Department of Agriculture to write regulations to provide for the use of the 134 kHz chip and reading wands in the US.
Only veterinarians can implant HomeAgain chips. AVID® chips can be implanted by shelter personnel, individuals, or veterinarians. Breeders often use the AVID® system because the company offers incentives to chip entire litters, but puppy buyers should be aware that the scanners used by many veterinarians come from HomeAgain and cannot read the number on AVID chips. Costs vary with these systems depending on the number of dogs owned and whether the dog is enrolled in the national database.
At the moment, the Banfield chip cannot be implanted in the company's 500-plus animal clinics, but that situation is likely to change if Congress approves the recommendation to adopt the 134kHz chip. Included in the recommendation is a requirement to develop a true universal scanner that can read all chips.
What does this mean to pet owners and breeders? Not a lot. There's no reason to assume that federal approval of a standardized chip will result in a mandate to use that chip. Current databases will continue to enroll dogs. Shelters and veterinarians will continue to scan dogs with the wands they have now and will likely switch to the universal wand when it is developed. As in the past, companies are likely to donate scanners to shelters and rescues.
* Destron-Fearing changed its name to Digital Angel.Corporation.
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