Recently someone informed me that microchipping your pet can give it cancer.  I initially brushed this off as yet another example of internet paranoia, and a complete misunderstanding of how microchips work, and of science in general.  After all, microchips do not have an active component.  They aren't transmitting your pet's information constantly - they have no power source, and do not emit any kind of radiation or radio waves.  A microchip is not a very small radio beacon.

Microchip tags are more like bar codes, or electronic key cards.  They are inactive bits of metal, which can be read by an electronic scan.  Pet microchip tags are very tiny circuit boards, which are imprinted with the number of the chip.  The circuit board is connected to a small capacitor and inductor, which allow the chip to draw power from the scanning wand.  When you pass the wand over the chip, the chip activates and sends its unique number to the wand.  Except when being actively scanned, the electronics involved are completely inert.

I went home and did a bit more research on the matter, and found that the answer is actually more complicated than you might think.  There is a very rare disorder which occurs in dogs, cats, and ferrets, called "pos tinjection sarcoma."  This form of cancer has only recently been discovered, and the precise cause is still unknown.  Put simply, in one out of every eleventy billion injections, a sarcoma (a malignant tumor) can form at the injection site.

In a very small subset of post injection sarcoma cases, the injection in question involved a microchip.  However, the incidence of microchip-related postinjection sarcoma cases are vanishingly small.  Furthermore, there's no way to know if it was really the microchip injection which caused the problem in the first place.  Since microchips are injected in the scruff of the neck - which is where every other injection is given.

Please do not let this dissuade you from vaccinating and microchipping your pets!  The risk is phenomenally small.  The number I found was 20 cases of postinjection sarcoma in the last 10 years, and it's anyone's guess how many injections overall were given in that same time.  Trillions.  Squillions.  A lot, is what I'm saying.

Furthermore, vaccinations and microchips are both incredibly important to your pet's health.  Your pet's risk of contracting rabies (from not being vaccinated) is about a million times higher than your pet's chances of getting postinjection sarcoma (from receiving the vaccination).  And needless to say, if your dog gets rabies, then the rest of your family is at risk of the same disease. 

Microchips are similarly valuable.  They can literally save your pet's life.  In most animal shelters across the country, new arrivals are given 72 hours before being euthanized.  That's a pretty short clock to find your pet before she's put to sleep!  You may feel that your dog or cat would never run away, but I have to point out - all those animals at the shelter?  That's what their owners thought, too. 

You may feel that your yard is secure, but what if someone walks past and opens the gate?  What if there's a big storm, and your cat gets spooked?  What if you're in a car accident, and your dog flees the car in an unfamiliar neighborhood?  There are too many "what ifs" to risk NOT microchipping your pet.