Microchips are generally implanted under the skin over the shoulder blades in dogs and cats. Each one contains an identification number unique to that animal; every microchip sold is automatically registered (to the vet who purchases it) in PETtrac, AVID's national recovery data base, according to Metzner.
She says private veterinary clinics on average charge from $60 to $100, and shelters from $20 to $30 (and often much less) to implant a microchip and register a pet for its lifetime. The chip is encapsulated in biocompatible glass (the type used in pacemakers, stents and other medical devices) and has been tested to last for at least 75 years, according to Metzner, who adds that AVID has sold more than 25 million microchips. Among other brands distributed in the U.S.: resQ, HomeAgain and 24PetWatch.
Some studies in the 1990s found that tumors formed in mice and rats in tissue around where the microchips were placed. But Metzner said further testing has produced no evidence of a link between cancer risk and the devices, which are only activated when scanned—and the U.S. Food and Drug Administration (FDA) in 2004 found the process safe enough to be used in animals and humans.
AVID, when contacted by Sonoma County Animal Care and Control, traced the device in George to Northtown Animal Hospital in Santa Rosa. Walburg says they were lucky their vet had their number, which had been changed since the chip was implanted and registered. In some cases, there is a more direct relationship with pet owners, who can change chip ID registration contact info online.
"Our sole purpose is to bring animals home. So it's a wonderful feeling to know that the system works," Metzner says about George's long-awaited homecoming. "It's a miracle. We get over 1,000 calls a day of people finding pets and reuniting them with families."
She says this is one of—if not the—longest period between a pet's loss and recovery ever recorded. Among other success stories: a cat that had been missing from Los Angeles for a decade, found in Texas several years ago, and a dog missing from Panama, Fla., who was found six years later in Ohio.
"There's no way this reunion after 13 and a half years would have happened without the microchip," Walburg stresses, urging all pet owners to chip their charges and anyone who finds a stray to take it to the nearest shelter or animal hospital to have it scanned for one. He also believes that vets should routinely scan their animal patients to make sure the humans bringing them in are their rightful owners, noting that they might have found George sooner had that been done.
"It's a very reasonable amount of money for something that potentially can help bring your pets home if they lose their collar. But even if your pet is micro-chipped, it's still important to have a visible collar and tag on that animal with the owner's name on it to get it home immediately," says Stephanie Shain, director of outreach at The Humane Society of the United States in Washington, D.C.
"It's pretty amazing," she adds about the George's homecoming. "If you're on the fence of whether you should or shouldn't get [a microchip], this would probably put a lot of people in the 'yes' column who weren't there before."