Chip Claim Gets Under Oncologists’ Skin

Claims of cancer in microchipped animals is causing public outcry from oncologists.

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Last month’s Associated Press news reports of microchips causing cancer in pets led to widespread media coverage. But veterinary experts say there is no evidence that cancer is a problem in microchipped pets.

A series of veterinary and toxicology studies dating from the mid-1990s purportedly showed that microchip implants had induced malignant tumors in some laboratory mice and rats. This, coupled with a case report documenting the death of a 9-year-old French bulldog due to a subcutaneous cancerous mass, was fuel for a denouncement of microchips, which were recently given the nod by the Food and Drug Administration for use in people with Alzheimer’s disease.

Cheryl London, DVM, oncologist at The Ohio State University, says she is enraged at the inaccuracies passed off as fact in the media reports.  She says she was misquoted in the  national report, and says the record needs to be set straight based on fact.

“In the 15 years I’ve been practicing, I have not seen one sarcoma in the neck area of a dog,” London says. “Millions of implanted microchips resulting in four cases is not evidence. Even if the four potential cases were scientifically determined to be linked to the microchip, the rate would be almost immeasurable at about 1 sarcoma and 2.5 million successes.”

Dr. London says when confirmation of feline sarcomas forming at injection sites was reported in the late 1990s, epidemiologic evidence existed and triggered further pathologist investigation. However, no such clinical evidence has been reported with microchips. As of yet, she says, there are no reports or need for concern.

“There couldn’t be a clinical study to investigate cancer caused or even possibly caused by microchips,” says Larry McGill, DVM, veterinary pathologist and technical vice president of ARUP Labs, American College of Veterinary Pathologists (ACVP) and AVMA chair member services committee.

 “We’re looking at four cases in question,” he notes.  This is all in consideration that 14 million-plus microchips have been used.”

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The case report of the bulldog’s dorsal mass was diagnosed as a high-grade infiltrative fibrosarcoma, morphologically similar to feline post-injection sarcomas, making the only medical link to microchips a geographical one, Dr. McGill says.

“There is a low incidence of sarcomas in surgical implants for people,” London adds. “But no one would suggest suspending a person’s pacemaker procedure. The possibility of four pets developing sarcomas at the site where a microchip was implanted isn’t even close to the rate of spontaneous sarcomas forming in pets. The benefits outweigh the risk.”

Professional Stance:

“The American Veterinary Medical Assn. endorses electronic aids in reuniting animals and owners,” says Rosemary LoGiudice, DVM, director of membership and field services, AVMA representative for the Coalition for Reuniting Pets and Families.

“This issue came up for this fist time in January and though it received less fanfare, the coalition met and discussed the reports. It was determined at that time, just as it is now, that the studies were flawed. The particular strain of mice used in the research is predisposed to cancer and not a reflection of the animals in the population.”

Dr. LoGiudice says the bigger problem is that not all microchip scanners read all chips.

“It would be a wiser course of action to put energy into an actual issue instead of drumming up accusations where there is no cause for alarm. This is a non-issue.”

Kim Selting, DVM, a veterinary oncologist at the University of Missouri,  Columbia, says before the news report, she hadn’t heard of any indications of concern about pets’ microchips.

“This issue is being sensationalized because of some concerns over FDA’s approval for human microchips,” Dr. Selting says. “There isn’t a concern for pets and I have never suspected a microchip as being the cause of any cancer I’ve treated in patients.”

London and McGill concur that the hype can be attributed to the FDA’s approval for human microchips.

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Dane County Humane Society, a Wisconsin animal rescue facility that finds homes for more than 300 pets a month, all of which receive microchips, has never received one reported concern.

“Many rescue groups and shelters have made microchip implantation part of their adoption protocol, just as the need for altering pets has gained attention in the past decade,”  says Gayle Viney, public relations and development coordinator for the society. “Veterinary hospitals and animal organizations across the board have sponsored microchipping clinics, and adverse reactions have not been reported.”


Morris Animal Foundation attracts researchers investigating diseases at the forefront of medicine and has funded almost 1,400 studies since 1948, amounting to more than $51 million in grant money.

“No grant money has been allotted to microchipping linked to cancer,” says Heidi Jeter, director of communications. “There isn’t a request for the research.”


McGill says about 8,000 pets a month are returned to their owners in the U.S. thanks to microchips. He labels microchips a necessity in today’s society and a benefit to pets, owners, animals and communities alike.

“If I could give one suggestion, even though there is not evidence or indication of a need to change protocol, I would recommend altering either the placement of microchips or the site used to administer vaccines,” McGill says.

“This would simply be a precautionary action, and one that would give a more accurate indication a sarcoma formed due to injections or a microchip.”

LoGiudice says the coalition will stay vigilant to see if any science appears to indicate there could be a cancer link, but there are currently no reports citing a problem.

Barbara McGehee, executive director, Veterinary Cancer Society, says she was aware of talk of a cancer link to microchips, but hasn’t seen firm evidence and the society has not taken a stance on the claim.

VeriChip Corp, whose stock plummeted as much as 14 percent one day after the release of the news service report, responded to the article and claims made against its  microchip.

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“The article and the alleged research cited make no link whatsoever to malignant tumor formation in dogs and cats but for one unsubstantiated report. It is important to note this report was not a controlled, scientific study, rather it was a report of a single dog that presented with a tumor, and therefore it should not be inferred that the microchip caused the tumor without further study,” the company says in a press release.

The FDA stands firm on its approval of microchipping.


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