Breaking news! Have you heard? It’s suddenly big news that microchips in pets can cause cancer. There’s one reported case out of hundreds of thousands of  microchipped pets. But mice, apparently, show an impressive susceptibility to cancer at the microchip injection site, according to research the microchip industry allegedly buried for fear its chips wouldn’t get skin-time in humans and pets.

Remember my microchip series? I didn’t much touch on the safety of these implants, seeing as I’d never heard of a reaction. Jeanne (she only sent me her first name), though, emailed me with her little French Bulldog Leon’s story and urged me to consider the possibility that Leon’s might be the index case for microchip-related cancer in pets.

I had no doubt when I read the article in Veterinary Pathology (a respected, peer-reviewed journal) that this was a real-live case of fibrosarcoma induced by a foreign body—in this incident, apparently the microchip. Leon didn’t make it. But his story lives on in Jeanne's memorial website, a cautionary tale for those who think anything implanted or injected by doctors is 100% safe.

Fibrosarcomas are a common tumor implicated in vaccine reactions in pets (read my post on the new research into this issue in felines). Now it’s become a human and pet issue, too, with the breaking news of two studies in mice that show cancer can result at the microchip injection site. So you know, humans are often microchipped when they have serious dementia (and risk getting lost). Perhaps that’s why this issue has received so much press once it was revealed that the microchip companies were apparently hiding this data. (Pets aren’t always big news but pets and humans, too?—now that’s a story!)

Leon’s case is a perfect example of how animal bodies can mysteriously respond to foreign objects in aberrant ways. Nothing is completely safe—not the herbs, not the gold beads used in acupuncture (also found to cause serious reactions in some cases), not vaccines and not microchips.

Every action has a potential reaction. And Leon’s case is the only example of cancer in pets (that we know of) as a potential result of a microchip (he was vaccinated the same day in a nearby spot so it’s not completely clear that the microchip caused it, though the cancer seemed to emanate from that one spot). Still, his case should give us some pause…and some solace, too, that with all the microchips implanted we've only seen one so far (that we know of).

Though I’m 100% sympathetic to Jeanne’s tragedy, I don't want to to fan the flames of microchip-naysayers everywhere. It's still an excellent tool--which we must now  approach with more caution. As with every medical implant, there's always a risk and the risk-benefit ratio must be weighed accordingly--with all the information at our disposal.

Now that it’s all over the news that rodents get cancer as a result of microchips (two studies in mice), the question should be: Why didn’t anyone tell us before this? I’d certainly never heard of the issue until I wrote my microchip articles and Jeanne clued me in (the power of the blogosphere never fails to amaze me). Dow Chemicals (which markets its VeriChip for humans) seems to have known of these cancer studies. Sure, mice aren’t people—or pets—but it’s not as if this information isn’t relevant.

If I’d known of the mouse studies I might well have had further cause to give my clients more choices by way of informed consent. Indeed, even Leon’s sole case found me talking with clients about adverse possibilities—though I always couched it in terms of “one case only.”

Armed with this new information, I now have more reason to discuss the issue more carefully with my clients. Just as with vaccines, I still believe the safety provided by the microchip is worth the risk. Nonetheless, pet owners should be granted the right to make their decision based on all the information available. And that’s why I think the microchip companies deserve whatever media fallout they’ll get from this issue.

If you hide anything, eventually it’ll see the light. Give people transparency and choices and they’ll respect you in the morning. The microchip companies failed us in this regard and I hope they feel the consequences of their irresponsible omissions.

There’s nothing worse than wondering whether you’d have made a different decision if you had all the facts at your disposal. Jeanne knows how this feels. So if you still choose to implant a microchip in your pet (and I think you should—I’d do it for mine if I had to do it all over again) then at least you’ll know you did so with a complete understanding of the risks involved, minimal though they seem to be.

I’ve been informed that this issue will air on ABC’s Tuesday morning programming. Watch for it and make up your own mind.