Pet ID Week April 18-24

There are a lot of pet-related events this month, so I need to get started on mentioning them early.
In honor of Pet ID Week, I want to talk about microchips. This has been on my mind anyway, as my niece has a new Rottweiler and told me that she isn't having him microchipped because she lost her previous two Rotts to cancer at early ages and "the only thing they had in common was being microchipped." Well no, actually, they had quite a large other thing in common -- they were Rottweilers.
This got me searching the Internet, and I came up with an excellent document put out by the American Veterinary Medical Association. You can find it on their website, and redistribution is okay as long as the source is identified. It's from October 2009, called "Microchipping of Animals."
It includes a section on adverse microchip reactions. They tracked reports of adverse reactions in the United Kingdom, where more than 3.7 million pets are microchipped, from 1996 through 2009. Migration of the chip was by far the most common complaint, with swelling, infection, and chip failure much more distant chances. There was one report of a tumor in 2003 and 1 in 2005.
The article then goes on to a specific section addressing cancer. It points out that the reports of mice developing tumors around chip injection sites have no correlation to dogs, as the strains of mice are particularly prone to developing foreign body-induced tumors. They also note that the site of chip implantation is often also the site for giving vaccinations, and thus the cause of any tumor is difficult to identify.
On the other hand, over the years, chips have become much more valuable and reliable as universal scanners have become available. They note that owners of unchipped dogs who searched for a lost dog were successful only 13% of the time, but a chipped dog turned in to a shelter was reunited with the owner 74% of the time. One of the recommendations put forth as a result of the 2006 National Animal Disaster Summit was that all animals rescued during a disaster be chipped if they weren't already, largely because after Hurricanes Katrina and Rita, microships helped identify rescued animals. (Finding their owners in the aftermath of the hurricanes was another matter.)
We recently had a demonstration of how effective the universal scanners are, as Teddy was microchipped in Taiwan and our veterinarian's scanner read the chip just fine.
The odds of losing a dog are much much greater than the odds of a dog developing cancer because of a microchip. Do yourself and your dogs a favor and have them chipped.