When the Chips are Down - are Microchips Hazardous to your Dog’s Health?

I was sitting having brunch with my family last Sunday when my cell rang. On the other end of the line was a producer from ABC’s Good Morning America. She told me excitedly about a hot-off-the-press AP article claiming that microchips were potentially cancer-causing and asked me if I would be prepared to comment on camera. I tried to pass the buck this time because oncology is not my area of expertise, but she insisted. (I don’t think anyone else was available at the weekend). I was to be the token vet.  I agreed to comment if she sent me the AP article and, if possible, the original research articles that led to the contention. She agreed and I had all of 3 hours to get home, read up on the subject, and set up my living room for the arrival of the film crew.

What I read was disturbing. Studies in rats and mice dating back to the 1990s showed quite conclusively that 1-10 percent of these critters, when implanted with microchips, developed cancers at the site, usually sarcomas, and some were malignant. One explanation was that the implant acted as a nidus of irritation and thus inflammation that eventually morphed into cancer.

The reason AP was so up in arms about the issue was that microchip technology is now being applied to humans – about 2000 to date. Microchips implanted in a person’s upper arm can be scanned to, say, identify wandering Alzheimer disease patient or reveal the full medical history of a person unable to communicate because of disease or injury.

Why had the medical device manufacturer, Verichip, not done its homework before implanting the chip into people? How had the FDA given approval for such technology without looking at the existing evidence (of which they claimed they were unaware).  That is a crock and one that slipped by under a cabinet member ’s watch. The same cabinet member who, incidentally, resigned to join Verichip and received generous remuneration from the company in return.

But political intrigue aside, what about the risk to our dogs and cats? Implantable microchips had been becoming increasingly popular for identifying “found pets,” ensuring that their return to rightful owners. Thousands of dogs and cats have been implanted with these rice grain-sized devices. The upside of their use is that properly identified pets do not get rehomed incorrectly or, worse, put to sleep so the chips can be positively life saving.

But what about the cancer risk?  Has cancer related to microchip implants ever been reported in dogs?  The answer is yes – but only twice. That doesn’t mean microchip-related cancer has only occurred twice. The reports may be the tip of an iceberg of a problem that will only be properly quantitated once the risk is recognized and vets are on the lookout for it. 

That said it does seem that the incidence of microchip-related cancer in dogs and cats must be considerably lower than in their relatively cancer-prone rodent cousins. At this time (and this is what I said on camera) it is too early to panic. Implanted chips probably save many more dogs than they harm – and life is all about the balance of risk and reward. We drive cars, don’t we?  On the other side of the coin are human cancer specialists who were interviewed for the AP piece. They said that they would never allow any member of their family to be micro chipped in light of the laboratory animal evidence. But then their family members probably don’t leap out of 2nd story windows during storms or roam the neighborhood looking for a pile of horse pucky to roll in and most have the gift of speech. People who have had their dog microchipped have probably done the right thing and they should not feel guilty. People planning on having their dog microchipped should probably not change their plans. However, it does make sense to check the site of the implant occasionally (every 6 months or so) to ensure no swelling is developing.  In the unlikely case that a lump is found, early removal will probably resolve the problem.                 

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