Many people incorrectly believe that the implantable microchips used as a means of permanent animal identification cause cancer. The cancer rumor is claimed to be based on solid scientific research, but it’s misleading.
The research reporting malignant and premalignant growths following microchip implantation was referring to mice and rats being used in cancer and chemotherapy research. However, cancer researchers use specific strains of mice and rats that are prone to developing malignant tumors.
Nothing in the microchips used in animals is known to cause cancer. Microchips don’t emit radiation or any form of energy. They don’t interact with or degrade in contact with body tissues.
Details on the types of chips used in the mice and rats were missing from the abstracts of the studies, but since the tumors they found typically took a long time to develop — close to the natural life span of the rats and mice — a possible trigger in these tumor-prone rodents is the trauma of having the chips inserted. Some people develop malignant tumors at sites of chronic wounds after long periods (25+ years) of time, and there are rare reports of tumors developing after implants, such as bone pins or joint replacements, but it’s almost exclusively in people with a history of cancer elsewhere.
The types of tumors found would be unusual in a horse. They’re seen with more frequency in dogs and cats, but dogs and cats have had microchips implanted for a lot longer and in higher numbers than in horses without this connection. Even in countries like Israel where microchipping of dogs is mandatory, there have been no observed problems with malignant tumors at microchip sites. Microchipping of race horses is required by law in South Africa and, again, no reports of malignant growths.
A horse with a history or family history of cancers might be a riskier candidate for microchip implants, but for horses in general there’s simply no reason to believe this is a concern.
Microchipping has returned many small pets to their rightful owners, especially if stolen. The same could hold true for horses, as more horse owners take advantage of the technology.