The Irreverent Vet Speaks out on “Do Microchips Cause Cancer in Dogs?”

Are microchips dangerous? Do they cause cancer in dogs and cats? As the irreverent veterinarian, I’ll work to give you information and alternative opinions about controversial topics. Here is information about the controversy surrounding dog and cat microchips.

Microchipping is widely used and a very successful method for identifying dogs. Recently, reports have been in the media about microchips that may cause cancer.

Microchips are FDA approved devices used for permanent identification of pets. The chip is small, compact and easily inserted under the skin. Lost pets are “scanned” and the chip identifies a number that can be subsequently traced back to the owner. Millions of pets have been microchipped and approximately 2,000 devices have been implanted in humans worldwide (with the goal of implanting 45 million people in the U.S) without significant problems being reported.

Studies about the effects of microchip implantation have been going on for about 6 years after implantation. Mild inflammation was noted in some animals but most was gone within 3 months after implantation. There have been some reported adverse reactions in mice and rat studies. Reports surfaced that the glass-encapsulated RFID transponders microchips caused malignant, fast-growing, lethal cancers in up to 1% to 10% of cases in rats and mice. In 2004, a dog was examined for a mass over his shoulder area. The mass was removed and was found to be a sarcoma. Attached to the mass was a microchip. The dog had no reoccurrence and is apparently well. In this case, according to the abstract published in Veterinary Pathology, it was difficult to establish which was the primary cause of the neoplastic growth, because the dog had received several rabies vaccines and the microchip was detected close to but not included in the mass. A concause could then be hypothesized.

The question is…

Do microchips cause cancer in dogs and cats?

The answer is – we don’t really know. There has been one reported case that they suspect the microchip could have been a problem but the dog was also vaccinated for rabies and a definite cause could not be determined. Are there more cases that have not yet been diagnosed? I don’t know.

What should you do if your pet has a microchip?

I’d recommend having your pet scanned during his routine exam at your veterinarian’s office. Chips are generally injected over the back but can migrate from over the back to the sides. By scanning the pet, you will be able to determine if the chip works and the location of the chip. Then I’d recommend feeling that area (just as women would do a self-breast exam) for the presence of a mass or problem on a regular basis. If you feel any sort of mass, see your veterinarian immediately.

My Final Thoughts – Should you microchip your dog?

Absolutely Yes! microchips are the best way of permanent identification of dogs. The chips are considered reliable and an effective way to identify lost pets. At this point in time, we believe that they likelihood of a pet being lost and possibly being euthanized because he cannot be identified is way higher than the chance of the pet developing a tumor.

I suspect there will be lots of new information about this as time goes on. I’ll keep you informed.


The Irreverent Vet is a columnist that regularly contributes to The goal is to add a balanced and alternative view of some controversial pet issues. As happens with all of us, veterinarians can’t say what they really think without offending some clients. This commentary allows vets to say what they think and give you, the pet owner, and the opportunity to consider another view. All opinions are those of the Politically Incorrect Vet and not the views of and are not endorsed by