Microchipping Your Pet

Chipping has become a routine procedure that in some areas is even required by law. But are they safe? Do they really cause cancer?

To put it simply, there is a risk but it appears extremely rare for a microchip to cause any serious or permanent damage. The risk is insignificant and it's worth that risk to microchip. Microchips reunite pets with their owners every single day. HomeAgain's website claims "Every month, HomeAgain reunites 10,000 pets with the people that love them," and over a million pets have been reunited with their owners through HomeAgain.

That's nice, but what about the risks? You're sticking something under your pet's skin. It can migrate, a cancerous tumor can grow around it, and there can be fatal or permanent complications. Fear not! These are all very rare incidences. An extremely small percentage of pets get tumors or cancerous growths around the chip.

Note: Many of the sources I've cited are anti-microchip sites because they have many of the studies and rare incidences all in one place. I am not anti-microchipping and in fact strongly support chipping; I believe the risk is insignificant as microchips save hundreds and hundreds of lives every day.

If nothing else, read this. This is the bottom line. Keep it in mind as you continue:

"Microchips have been used extensively in pets over the last decade. They are especially prevalent in the United Kingdom, where over four million cats and dogs have received the implants. The British Small Animal Veterinary Association has been tracking adverse reactions to microchips since 1996. They identified a link between microchips and cancer in two dogs.
Two dogs out of four million is a very low number indeed.

It turns out that the strains of mice and rats cited in the studies that first noted the microchip-cancer link had been developed to be especially prone to cancer. In these animals, microchips caused tumors at very high rates. So did anything else that was implanted under the skin. In this case, it may not be appropriate to draw a direct link between these rodents and household pets." [source]

What percentage is 2 of 4,000,000? It's 0.00005%. I hope you'll remember that bottom line. Microchips carry a risk, but the risk of losing your pet is immensely greater than the risk of cancer or adverse affects caused by the chip.

"You can treat most cancers," wrote a dog enthusiast in a recent online debate about microchipping. "You can't treat a no-kill shelter's last-day policy." 

Do Microchips Cause Cancer?

The studies that have been conducted concerning cancer and microchips are not reliable studies.

"A 1998 study of 177 mice reported an incidence of cancer of just over 10 percent. A French study in 2006 noted tumors in 4.1 percent of 1,260 microchipped mice. And a German study in 1997 linked cancer to microchips in 1 percent of 4,279 mice.

None of the studies had control groups of nonchipped mice, which means that there were no "normal" cancer rates to use as a comparison." [source]

Most tumors/cancer are found between the shoulder blades, where the chip is implanted- but that is also the site of vaccinations which is another thing to think about.

As far as I know, there are no scientific studies about microchips that are done with dogs. There are case studies but the experiments are all rats or mice with no control groups, so you can't tell what the difference is. Even if 10% of mice got cancer with a chip, maybe 9.8% would get cancer anyway without a chip. Or maybe only 1.4% would. You don't know. You need a control group and to use the right kind of mice. Can mice compare to dogs anyway?

There are a couple case studies of dogs who had a malignant cancerous tumor attached to/surrounding the microchip. It could be from any number of other things, including (over)vaccination, but it very well could be a direct result of the microchip and it does appear that way.
Dog 1: http://www.antichips.com/cancer/02-vascellari-et-al-fibrosarcoma-2006-overview.pdf

Dog 2: http://www.antichips.com/cancer/03-vascellari-et-al-liposarcoma-2004-overview.pdf
 

Here is the larger study which included these two dogs, as well as 9 other studies on rodents. Again, keep in mind the rodents studied were prone to cancer and there were no control groups.
http://www.chipmenot.org/pdfs/P074.pdf

Are There Risks Other Than Cancer?

Unfortunately yes, and they can have quite horrible outcomes. There are other very rare occurrences not related to cancer or tumors I've come across, when the microchip is being inserted.

In 2009 a Chihuahua bled to death through the tiny hole created by inserting the chip. Read the full story here. My gut reaction was that the dog must have had a blood clotting disorder or something wrong but it's important to note that the dog did not have a blood clotting disorder as he had previously undergone neutering and a tooth extraction. As mentioned in the story, the space between the shoulderblades is not known to have any major blood vessels. The vet is unsure of why the dog bled so profusely, and was not held at fault.

In 2004 a struggling kitten died immediately after being microchipped, and in another case a cat was neurologically damaged.

"A post-mortemexamination later revealed that the microchip had been accidentally inserted into the kitten's brainstem(BSAVA, 2004).

In another case a cat suffered severe neurological damage when a microchip was accidentally injected into its spinal column (Platt et al., 2006)" [source]

These incidences of cancer, tumors, death, and permanent damage are tragic to say the least. Microchips are designed to save lives, not cause harm. I've said the risk is insignificant. The risk is insignificant until it's your pet. Until your dog is bleeding out, until your dog has cancer. That is significant and a sobering thought. I still stand by my statement of fully supporting microchips. As of now, based on the science and literature available, every pet I own will be microchipped. Chips save lives. That is the case every day- lives are saved. Remember how HomeAgain saves 10,000 pets a month? On average over 330 pets are reunited with their owners every single day, and that's just one microchip company. I'm not going to be overly worried or intimidated by a 0.00005% risk.

I Don't Want to Microchip! What Can I Do?

One of the best alternatives to microchipping is tattooing. An identification number is typically tattooed on the pet's inner thigh or the inside of the ear. It takes only a couple minutes and therefore pets are not anesthetized for this procedure. Anesthesia carries a risk in itself. If your pet is going under for a spay/neuter or another procedure it would be a good time to get the tattoo done however your pet does not need to be under for a tattoo. There is claim that the procedure does not hurt as pet skin is different from our own but I'm not sure I believe that. Pinch your dog's skin and guess what? He doesn't like that because it hurts. Speaking from personal experience, having a vibrating needle under your skin hurts and the vibration itself is an odd sensation that I imagine a pet may not appreciate.

Tattoos can fade but the number can be reapplied. Dogs with furry inner thighs must be kept shaved or trimmed very short there so the number can be visible.

Find out more information at the National Dog Registry.