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Saturday, January 8, 2011

Microchips & Tumors

In 2007 a press report stated that there was a direct relationship between microchips and certain tumors in mice, rats, and dogs. Depending on the studies reviewed, tumors happened in anywhere from 1-10% of the animals who had chips implanted. This article has caused an uproar and concern in those who have read it. Now there are people who are extremely concerned that microchips will cause tumors in their pets.

However, I haven't seen any good evidence that this is a true risk. Here are some quotes from the original article, which I think are overlooked in the discussion.

Dr. Cheryl London, a veterinarian oncologist at Ohio State University, noted: "It's much easier to cause cancer in mice than it is in people. So it may be that what you're seeing in mice represents an exaggerated phenomenon of what may occur in people."

Tens of thousands of dogs have been chipped, she said, and veterinary pathologists haven't reported outbreaks of related sarcomas in the area of the neck, where canine implants are often done. (Published reports detailing malignant tumors in two chipped dogs turned up in AP's four-month examination of research on chips and health. In one dog, the researchers said cancer appeared linked to the presence of the embedded chip; in the other, the cancer's cause was uncertain.)

A Time article had more interesting quotes.

In an exclusive interview with TIME, Silverman provided a list of 34 studies the company included in its FDA application, including one of the three mentioned in the AP article, which showed that less than 1% of 4,279 chipped mice developed tumors "clearly due to the implanted microchips" but were otherwise healthy, and that "no clinical symptoms except the nodule on their backs were shown." The second study, conducted in France in 2006, two years after VeriChip's FDA application was approved, found that while 4% of the 1,260 mice in the study developed tumors, none of them were malignant. As for the third study, Silverman says it was conducted in mice specifically bred to produce tumors, and was therefore omitted from the sheaf of studies included in the FDA application.

Dr. Lawrence D. McGill, a veterinarian and leading expert in animal pathology says the tumor development in rodents is unsurprising. "Even if you put in a bland piece of plastic, it will produce tumors in rats and mice," says McGill, who assessed the studies on behalf of VeriChip. He says it would be a leap to apply the findings of studies in mice to cats or dogs — or to humans, for that matter — which are much more complex animals. Few official scientific studies have been conducted on the effects of microchip implants on house pets, but none have found a link between the chips and cancer, says McGill. If there were a problem, he says, we would have already seen lots of cancer among the approximately 10 million pets that have been chipped over the past 15 years. Says Silverman, "There are no reported incidents to the FDA of any cancer formation around that."

The American Veterinary Medical Association did release a position statement shortly after the original article came out.

In a Sept. 13 statement posted online, the AVMA said staff and member veterinarians are actively looking into the potential for electronic identification implants to induce tumors in dogs, cats, or people but must await more definitive data and test results before taking further action.

Considering how a large number of pets have been implanted with microchips with a relatively small number of confirmed cases of tumors associated with microchips, the AVMA advises against a rush to judgment on the technology.

In fact, there is a concern among veterinary medical researchers that some of the research into supposed chip-induced tumors may be flawed, because the animals used were genetically predisposed to cancer. In addition, removal of the chip is a more invasive procedure and not without potential complications.

The Time article further quotes a representative of the AVMA.

The AVMA officially counsels against removing the chip, while assuring pet owners it will continue to monitor the situation. "At this point we do not recommend that people should stop microchipping," says Dr. Rosemary LoGiudice, a veterinarian and assistant director with the AVMA. "We are actively watching. For the number of animals that are said to actually have microchips, when you consider the number of animals that have been microchipped and returned to their owners, the benefits are huge compared to the few and suspect cases that have been reported to have tumor formation."

Personally, I don't think there is a large enough risk of tumors to be concerned.  Is the potential there?  Quite possibly.  However, there really is nothing out there without any risk at all.  Vaccines, routine surgeries, antibiotics...they all carry some risk.  Some time read the warnings and side-effects on a label of ibuprofen or aspirin, and you may be surprised and scared.  No matter what medicine we take or procedure we undergo, there will be various degrees of risk.  Thankfully, most of the time nothing adverse happens.  So there could be minor risk in some patients, but I see no evidence that it's a worry for the majority of pet owners.

In my years of practice I have never seen any tumor associated with a microchip or talked to any other vet who has seen it.  Millions of pets and livestock world-wide have received microchips, yet there are no reports of wide-spread tumors.  In fact, this one 2007 article is the only I've ever heard of that has looked into the issue, and if it was really a true concern, I would think that more data would have come out in the three years since it was published.

I know that there are some people who are vehemently opposed to microchips, and I'm sure that I won't convince them otherwise.  But based on the available data I think that microchips are overall safe.  I recommend them to my own clients, and believe in them enough to implant them in my own pets.


  1. Chip mfgs should be required to warn of the risks instead of saying the product is 100% safe.....lose a pet to cancer, with the chip in the middle of the tumor that was removed, and you'll think differently about chipping....see for more reports on cancer and the deadly results of microchips

  2. Look at the numbers, though. Most of the data on tumors in animals is based on findings in mice. The physiology is different than a dog or a cat, and many research mice are genetically predisposed to cancer. Also, some of the articles referenced on that web site discuss improperly implanted chips that end up in the spine. This is the fault of the implanter and not the chip itself. If a dog dies from blood loss because a vet didn't tie off blood vessels properly during a spay, it doesn't mean that spays overall aren't safe.

    Numbers...ChipMeNot gives case studies of animals with tumors associated with microchips. They list 11 dogs, 4 cats, 3 horses, and 4 zoo animals of various species. There are dozens of rodents reported, but again many of these animals are more prone to tumors than dogs at cats. So of common companion animals, there are 18 cases. If you look at the articles listed on that site as evidence and look at only the papers on dogs and cats, almost all of them are single cases (specifically 4 cases). Most of the other articles are related to mice and other rodents (more prone to cancer, remember).

    Numbers...So of all of the articles and cases reported on this specific site, we're looking at around 25 cases. Now let's say that this is not a representative sample, and let's inflate that number 1000-fold (a huge assumption and number). That's about 2500 tumors related to microchips. Remember that microchips are commonly implanted in pets, livestock, and zoo animals. So by some estimates, around 10 million animals have had microchips implanted. Do the math...that's 0.025% of microchips that have lead to tumors. Which means that conversely 99.975% of animals have safely had tumors implanted without any resulting cancer. Think my numbers are too conservative? Then let's inflate ChipMeNot's numbers by 10,000! Remember, these numbers include quoted articles and not just the scant case reports. 25,000 tumors would also include every tumor reported in mice and rodents, not limiting it to companion animals, plus thousands more that aren't in the literature or reported. Pretty generous numbers, right? That still results in a 0.25% incidence rate of tumors. Think the 10 million number is too high? Okay, decrease it by 10-fold to 1 million and keep the 25,000 tumors (which I think would be very high). You still get a 97.5% chance of being fine with a microchip.

    Looking at it this way, I think the chance of tumors is very highly unlikely. Can it happen? Sure. But you'll probably find a higher adverse event rate with aspirin and ibuprofen, both of which we consider safe medications. Even playing with the numbers to over-inflate the tumors and under-report the chips implanted they are still overwhelmingly safe.

    If we were seeing wide-spread tumors due to microchips there would be much talk about it in the veterinary community, and I've seen none of that. I've seen veterinary medicines and pet foods recalled for less than 1000 cases of problems, and usually less than 100 cases. Heck, food recalls have happened because of the CONCERN for problems, even without specific cases reported. Believe me, pharmaceutical and pet food manufacturers have more money and influence than microchip companies, and their products have been recalled. Yet there have not been any recalls of microchips.

    Put it all together. Look at ALL of the case reports, lack of worry in the veterinary community, total number of microchips implanted world-wide, and relatively small influence of manufacturers to keep bad news out of the public eye. I firmly believe that in the huge majority of cases microchips are very safe. Deaths and complication rates are much higher in other procedures we consider safe and common.

    And as a biologist, scientist, and medical professional, I will continue to put them in my own pets.

  3. Here is a small sample of four stories of dogs that died because of problems associated with implantable microchips. The names of the beautiful, devoted and healthy dogs that passed away are Léon, Seamus, Scotty and Charlie Brown.

    Léon - A French bulldog developed an aggressive form of cancer at the site of his microchip implant. Here is what Léon's owner says:

    "The more I learn about microchip implants, the more I am horrified that mandatory microchipping of animals is being enacted ... No one has the right to force pet owners to have a foreign object implanted in their animal, particularly when scientific data proves there are many health risks associated with the device."

    Seamus - A five-year-old bull mastiff developed a 4.3 pound cancerous growth at the site of two microchip implants and subsequently passed away. Here is what Seamus' owner says:

    "I got the microchip because I didn't want him stolen. I thought I was doing right. There were never any warnings about what a microchip could do, but I saw it first-hand. That cancer was something I could see growing every day, and I could see it taking his life ... It just ate him up."

    Scotty - A five-year-old Yorkshire terrier developed cancer at the site of his microchip implant. Scotty died last month (May 2010). His owner says:

    "I did something I thought a responsible pet owner should do - microchip your pet - and to think that it killed him ... It just breaks my heart."

    Charlie Brown - A long-haired, pure-bred Chihuahua bled to death in the arms of his owner just hours after he received a microchip implant. His owner says:

    "I wasn't in favor of getting Charlie chipped, but it was the law ... This technology is supposedly so great until it's your animal that dies ... I can't believe Charlie is gone. I'm just beside myself."

    The suffering of these dogs was unnecessary and heart-breaking. The only thing these pet owners can hope for is that their stories will prevent other animals from experiencing the same fate.

  4. The fact that any animals are affected at all, will keep me from putting a chip in my pet. Why take the chance? Here's another site with info.

  5. The biggest flaw by Chris Bern that is story is based on assumption.
    Yes mice and rats are more vulnerable to cancer then higher life forms. And yes some of the researched animals were predisposed.
    What Bern does not say that this is common practise, just because to test whether a certain may occur.

    Development of cancers on higher lifeforms can take up for years. For examle if i smoke i will not development cancer in a few years time. That may take 20 years. So the fact that the number of reported incidents is low, is not a matter of chips being safe, but related to the slow development of the cancer. Bern argument is for that reason flaw

    Another reason why Bern reasoning is flaw is because there is no real research done on tracking an monitoring animals that are chip implanted. We only wait untill such cases represent themself. Which is difficult, because most vets in the field lack proper means to determine the relationship between cancer and a present chip. Bern should know that fundamentel research is required to determine that. As for that reason the side effects of ibuprofen is determined by fundamental lab and field research and not just merely by what one might discover. Especially if you consider that cancer is one of the most complicated diseases known to men. We hardly now how cancer work.

    So it very bold of Bern to state that chips are safe, while the proof of safety on short, mid or long term lacks.

    The resarch done on the small animals proofs that there are major concerns about the use of chips in animals and people. Instead of taking these concerns seriously, Bern only backs away.

    And when it comes to statistics: The use of Softenon had also a low impact on the total population. I dont have to explain how we feel these days about that medication. ie Low statistics at itself is not an argument to validate the use of chips. Fundamental research should be the base. And that is lacking up to this day.

  6. Again, I'm not denying that tumors can happen due to a microchip, and it's tragic when a pet dies unexpectedly. But like I mentioned before, look at the numbers. I can promise you that more pets have died due to complications from a spay or neuter surgery than have gotten cancer from microchips, yet there's no great outcry to have those procedures stopped.

    There is not a single procedure, surgery, or medicine we use that doesn't have the potential to cause an adverse reaction or even death. Everything we do in medicine carries some degree of risk, and there is NOTHING that doesn't have the potential to affect a patient in a bad way. When we give a medicine, perform a surgery, or do any other procedure we weight benefits versus risks and look at the complication rate. Analyzing it in this way I am very confident that though microchips can in VERY rare cases cause problems, they are overall safe.

    And as I stated in my original post, I know that I'm not going to convince those opposed to microchips. I hope that other people will look at the data more objectively.

  7. Firstly, the argument is risk analysis carried out by companies who sell a product versus precaution advised in case where scientific certainty doesn’t exist [1]. The argument played out with most new technology products between big business who don’t want to test anything properly and activists who demand no change ever occurs unless mandated in the Bible. Both attitudes extremes based on financial greed and ideological positions respectively, not logic.

    Why would large population lifetime studies of diverse breeds and lines of dog be a bad idea? It is because it would interfere with profits. This is not about animal welfare; it is about the semiconductor industry needing sales and stabilizing demand by mandating the use of certain technologies in the Western World that stabilize markets in segments as diverse as gold and electronics.

    What worries me is the old tobacco PR lines I hear trotted out. I think we know science abuse exists when profits are at stake. One example being the tobacco industry research on smoking and cigarette toxicity [2] [3]. I hope everyone agrees that outright lying and deliberate confusion and weasel words have no place in a scientific assessment of microchip implants. Let’s have an honest discussion. We have not had this so far.


    [1] THE PRECAUTIONARY PRINCIPLE IN ACTION A HANDBOOK First Edition Written for the Science and Environmental Health Network By Joel Tickner – Lowell Center for Sustainable Production
    Carolyn Raffensperger – Science and Environmental Health Network and Nancy Myers

    [2] Secret science: tobacco industry research on smoking behaviour and cigarette toxicity David Hammond PhD a Corresponding AuthorEmail Address, Neil E Collishaw MA b, Cynthia Callard MM b

    [3] Big tobacco is watching: British American Tobacco's surveillance and information concealment at the Guildford depository Monique E Muggli MPH a, Eric M LeGresley LLM b, Dr Richard D Hurt MD c

  8. Chris let talk about objectivity.

    Here is a quote from the WSAVA website,” The Executive Council and all the Veterinary community thanks our sponsor Bayer, Hill’s and Intervet whole heartedly.”

    Here is another one, ”From the very outset we have been strongly supported by Hill's Pet Nutrition, Intervet and Bayer Animal Health whose enthusiasm and financial commitment has enabled the programme to flourish.” [4]

    It is hard to evaluate anything objectively when heavily sponsored by the manufacturer of the evaluated product. I am sure you will agree.

    These people make micrchips and educate vets what is objective about that?

  9. 1. Risks associated with microchipping include but are not limited to: Cancer, neurological damage, death due to the implant procedure, abscesses, infections, failure of microchips, failure of scanners to detect and/or read microchip implants, rejection of microchip from the body, migration of chip from the original implant site, MRI issues, duplication of microchip numbers etc ...

    Published scientific reports and medical data regarding cancer, neurological damage and death due to the microchip implant procedure are available at

    2. The mice and rats that developed cancer because of their microchip implants were NOT bred to produce cancer. This is one of many lies started by the microchip industry after the microchip-cancer risk was publicly exposed in 2007 by AP reporter Todd Lewan. Unfortunately the lie has been perpetuated by the media and even veterinarians.

    For a well researched, in-depth look at the unethical behavior of the microchip industry and problems associated with microchipping, read the document "Microchip Implants: Technological Solution or 21st Century Nightmare?" It is available for free at

    3. Adverse reactions to microchip implants are not rare. Instead, adverse reactions to microchips are rarely reported.

    4. Dr. Bern: Why is mandatory microchip legislation being enacted yet it is not mandatory to report adverse or suspected adverse microchip reactions? Also, why aren't pet owners being advised of the risks associated with microchipping?

  10. Obviously we have strong opinions on both sides of this issue, and I knew that the opponents of microchips would be very vocal and would not be convinced otherwise.

    As far as the data in veterinary medicine, there isn't a wide call among veterinary specialists and researchers to stop placing microchips. The veterinary journals and conferences are not filled with debate and caution regarding microchips. Even if many adverse events were not reported, if it was as wide-spread as seems by these comments and articles it would be more widely discussed in the literature.

    As I've said, I don't deny that tumors can occur in rare circumstances. But based on the numbers, I don't think that the microchips are solely at risk. With injection-induced fibroscarcomas there is speculation that some pets have a genetic predisposition to cancer, and when you cause localized inflammation this tendency turns to fact. I think the same tendency may be a main factor in the issue we're discussing. In most pets microchips are safe and inert. But in individuals with an underlying tendency, they MAY lead to tumor development. Unfortunately we don't have a way to screen them at this time.

    So based on a lack of profession-wide concern, the huge number of microchips implanted without any concerns (in the milions), as well as my personal experience, I think that microchips are overall safe. I have reviewed all of the information that commenters have provided, and I will continue to microchip MY OWN pets, as well as recommend them to my clients.

  11. In the UK at least we implant in the scruff and anyone can implant after a three-hour course, you don’t even need the course to start implanting if you can access the equipment, which you can via internet auction sites. For a reaction to be registered the BSAVA sub-group MAG which is made up of interested parties has to accept it. They can ignore every reaction where vaccination occurs at the site of the implant. Since either the vaccination or the chip could cause the reaction this is an excellent way to dismiss unflattering data. If cancer is not at the site of the microchip they will dismiss the report, but metastasis is a feature of soft tissue sarcomas. So the system for catching reactions is flawed.

    Which is why you don’t see unflattering data in the UK can’t speak for the USA.

  12. Please join our efforts to prevent mandatory microchipping legislation by signing this petition:

  13. I have a dog I rescued from the shelter who has a cancerous tumor at the micro chip. Dr. Bern you say it's rare. Well for me I have never lost a dog in my 52 years and my dogs always have collars with ID. I rescue a dog that has a mandatory chip put in her and she has cancer. My first chip experience and this is what happens. It's very hard for me to believe this is as rare as everyone says. I think because there is no place tracking this it is not being reported.

  14. Valerie, I'm sorry that you lost your dog to cancer. But that's one single case. And people ARE tracking these things, as you can see in the data I presented in the original article 3 years ago. If you want to go by personal experience, I have had all of my own dogs and cats implanted with microchips, so far a total of 10 pets. None of them have had any adverse reactions to the chips and never developed tumors. But I've lost one dog and two cats to cancer, none of which had anything to do with the chip. I've also implanted hundreds of microchips over my career, and have seen hundreds more that have had chips implanted by other people. I've never seen any tumor develop at the implantation site or around the chip itself. So if you look at your "data", yes, microchips are horrible. If you look at my "data", microchips are harmless. You simply can't go by personal experience to assess wide-spread safety. And when you look at the epidemiological data, it just doesn't support microchips as being a high-risk procedure.


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