This week has seen a number of news articles reporting that your dog has an increased risk of cancer if he is microchipped. According to the articles, sarcomas – malignant tumors – can develop at the site where the chips are implanted.
Some of the articles have been sensational in nature, and there are reports of dog owners taking their dogs to the vet demanding to have microchips removed purely on the basis of what they’ve read in the press.
As responsible dog owners, we need to know all the available information so we can make an informed decision on whether or not to have our dogs microchipped, or if they are already microchipped, to have the chips removed.
Here are the facts as I understand them:
What has the fuss been about:
The United States’ Food and Drug Administration (FDA) approved the implant of microchips in humans in 2005 on the basis that it found “reasonable assurance” that microchips are safe.
However, neither the FDA nor VeriChip Corporation (who make the microchips) has publicly disclosed that a number of studies in the mid 1990s identified that microchip implants had caused malignant tumors in laboratory mice.
Both the FDA and VeriChip are denying they knew of the existence of these studies, despite the fact that the results were published in a number of veterinary an toxicology journals.
What were the findings of the studies done in the 1990s?
A 1997 study in Germany found 1% of 4,279 micro chipped mice developed cancers that, according to the authors, were “clearly due to the implanted micro chips”.
A 1998 study in Ridgefield, Connecticut reported that just more than 10% of 177 microchipped mice developed cancer, and this result was considered “surprising”.
In addition, a 2006 study in France found that 4.1% of 1,260 microchipped mice developed tumors. The study was not testing for the development of tumors, and as the discovery was incidental, the results may be underestimating the true occurrence.
Whilst none of the studies had a control group of mice that did not get microchipped, cancer specialists still maintain that the research raises a red flag on the link between between microchips and the malignant tumors that were found; in most cases the tumors were encasing the implant.
What’s the risk to dogs?
Apparently it’s easier to induce to cancer in mice than it is humans, and the inference is that dogs lay somewhere between mice and humans. Therefore the chances of your dog developing a malignant tumor from a microchip implant probably aren’t as high as the studies noted above. However, no research has been done to prove this one way or another.
Dr. Cheryl London, a veterinarian oncologist at Ohio State University, has noted that tens of thousands of dogs have been chipped, and veterinary pathologists haven’t reported outbreaks of related sarcomas in the area of the neck where the implants are usually done.
The Associated Press conducted a four month research into microchips and health and only identified two cases where chipped dogs developed malignant tumors at the site of the implant.
Leon, a French Bulldog is probably the most well known dog to have suffered from a sarcoma due to the publicity a memorial web site to him has received.
However, Leon’s owner states that the same day Leon received his chip he also had a vaccination near the same site as the implant. Given that vaccinations can often induce sarcomas, it’s not 100% certain that Leon’s tumor was caused by the microchip.
In the light of the available evidence, it appears that the risk of your dog developing a sarcoma is very low.
What’s the alternative to microchipping?
A dog should have some form of permanent identification – collars and tags simply aren’t reliable enough.
Tattooing is an alternative, but if your contact details change, then it’s harder to update these on your dog. With a microchip the new information can easily be scanned into the chip.
What can I do if my dog has already been microchipped?
One way to monitor your dog for the development of a sarcoma is to routinely check for lumps in the area where the implant was done.
Microchips can move, so it’s recommended that you check the area from elbow to elbow over your dog’s back.
To microchip or not
The evidence indicates there is some risk of your dog developing a malignant tumor following the implant of a microchip.
However, this has to weighed against the chances that your dog might get lost.
Dogs can easily become separated from you – think of how quickly a dog can run off after a car accident or house fire, or after being spooked by fireworks; natural disasters such as Hurricane Katrina saw many owners separated from their pets.
If your dog has some form of permanent identification, the chances of the two of you being reunited are much higher.
Less than 50% of lost pets are reunited with their owners – many pets find their way to animal shelters but if they have no form of identification there is a high probability they will be euthanized if they’re not claimed or adopted within a few days of arriving at the shelter.
For me, microchipping is the only option for my dogs because the risk of losing them is far higher than the chances they will develop a chip induced sarcoma.
Whatever you decide to do, at least you now have all the facts with which you can make a decision.
[tags]dogs and microchipping, sarcoma associated with microchipping, malignant tumor, microchipping risks[/tags]