Do Microchips Cause Cancer?

Here we go again... Studies conducted in the 1990’s suggesting microchips may cause cancer have recently resurfaced. This time published by the Associated Press, the story gained some momentum and was picked up by the New York Times, ABC News and other major media sources. The fact remains however that in the last 10 years, no evidence has been found that in any way demonstrates the existence of a correlation between microchip implantation and incidence of cancer in cats and dogs.

We asked for comments on the latest version of this story from one of the industry's leading voices, Dr Walt Ingwersen. For several years, Dr. Walt Ingwersen has been involved in discussions throughout the world regarding microchip implants for companion animals. He served as Editor of JAAHA (Journal of the American Animal Hospital Association) and has published a dozen articles on the subject. For the purposes of full disclosure, it should be noted that Dr. Ingwersen serves as an advisor to Pethealth Inc. from time to time:

"This is not a “microchips cause cancer issue” but rather that anything that gains entrance to the body and incites inflammation could be a trigger for cancer. This is extremely rare, although there appears to be a higher incidence in certain families or lines of animals indicating a genetic predisposition. This predisposition does not simply apply to microchips but to ALL products/items that end up in a subcutaneous location, including vaccines, foreign bodies, etc., and even trauma.

Additionally, the aforementioned studies were flawed from an epidemiological perspective because the rodents used (e.g., 4279 CBA/J mice) are genetically selected to be prone to cancer; therefore they are not representative of the general population of companion animals kept as pets. Additionally, it is well recognized that one cannot extrapolate from studies in one species (e.g., mice) to another (e.g., cats and dogs)

It is also important to know that work has been done to confirm the safety of microchips implanted into animals (see references below). A literature search only shows 2 case reports of a suspected inflammation-induced fibrosarcoma at the microchip implantation site, however there was not a definitive cause-effect conclusion as other injections had been given in the same area.

Additionally, the BSAVA (British Small Animal Veterinary Association) has had a robust microchip adverse reaction surveillance system in place for over 10 years with only 2 reports of cancer associated with a microchip implant. Again, there was no causality assessment provided and this may simply be a coincidental occurrence. Even so, based on all adverse reports received by the BSAVA, this only equates to a 0.6% incidence, which is extremely low, especially when one factors in the high rate of microchip use in the UK (the majority of dogs and cats are implanted with a microchip):

http://www.bsava.com/resources/microchipadvice/adversereactionform/

References:

• Murasugi, et al. Histological reactions to microchip implants in dogs. Vet rec 2003;153:328-330.

• Rao, et al. Tissue reaction to an implantable identification device in mice. Tox Path 1990;18:412-416.

• Ball, et al. Evaluation of a microchip implant system used for animal identification in rats. Lab Anim Sci 1991;41:185-186"

In the last year, thousands of animals have been reunited with their owners by 24PetWatch specialists through the use of microchips. We hope Dr. Ingwersen's response helps our clients understand a bit more about the issue and see that the benefits out-weigh the risks in this case.

 

The Pethealth Family

After adopting Freedom from our local shelter, we were informed that she was microchipped with 24PetWatch. At just nine months old, Freedom is a beautiful German Shepard-mix with a heart of gold. Unfortunately on the first night she came home with us, she got confused and ran out through the front gates. Something must have spooked her while she was playing with our boys and she just took off. After missing for three weeks, we had all but given up on ever finding our new, special dog. One day, we received a call from our humane society that Freedom was at last found! Aside from being really hungry, Freedom was virtually unharmed. Apparently she was found wandering near the airport many miles away. The fellow who found her checked the information on her collar, read that Freedom was microchipped, and took her to a local shelter. The 24PetWatch Microchip Identification Program saved Freedom's life. Without it, she could've been lost for good or put back into the system without anyone knowing she had a family that cares for her. I guess Freedom lives up to her name, but thanks to her microchip and 24PetWatch, our gentle dog will always have a place to call home. Client: Doreen Derrick, Oak Creek, Wisconsin