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Thursday, January 6, 2011

Microchip Failures?

Recently I received a question from Cindi, who is part of a poodle flickr group.  A discussion came up because several members of the group had found that the microchips implanted in their dogs could not be read.  I won't copy the entire discussion here, but this is a basic summary:  Several chips from different manufacturers in different pets and different geographical locations could not be read by multiple scanners.  Within a veterinary practice 2-3 different scanners were used and none of them could find the chip.  So obviously people are concerned about the microchips in their pets.  And this is a good and valid topic for discussion!

First, let me point you to a post I made in 2009 about the basics of microchips:  read this and then come back.  I won't repeat information from that post here, and it will give you good basic information about some of the current microchipping issues (which haven't changed since I wrote it).

Microchips function as passive transmitters.  The microchip itself has no battery or other power source.  Until activated it's basically an inert object that simply sits under the skin and does nothing.  The scanners broadcast a radio frequency over a short distance. Some scanners broadcast a specific frequency while most newer ones will broadcast multiple frequencies to cover different types of chips.  Each chip responds to only one specific frequency of radio wave.  When that frequency hits the chip, it gives it enough power to broadcast a small amount of data (its number) over a short distance.

Now there is a problem with microchips in the US because there are a couple of different competing frequencies (see my previous post).  Modern universal scanners should be able to read all frequencies.  However, there is one company, Avid, that has encoded their chips so only an Avid-brand scanner will read them.  There was even a controversy because all other microchip manufacturers agreed to unencode their chips so all scanners could read them, but in the US Avid refused to do so (even though they have different frequencies and open-read microchips outside of the US).  Some scanner companies found ways to "crack" the code and can now read Avid chips.  However, this isn't consistent or reliable, so in some cases an Avid microchip can only be read by an Avid scanner.  I'll be nice and not give my personal feelings about Avid because of this issue (though you can probably guess that I'm not a fan of them).

In my opinion, microchip failure is very rare, and overall they are one of the best ways of identifying your pet if lost.  I believe in them enough that I have microchipped all of my own pets, and will continue to do so.  However, a microchip is an electronic device, and any such device does have a chance of failing.  It's a fact of the laws of entropy that any mechanical or electronic object has the potential of breaking down.  You can manufacture an object to be very reliable and have a low chance of failure, but it's impossible to make something that will never stop working.

Personally I haven't seen or read any reports of wide-spread microchip failures.  There has been nothing reported in any of the US veterinary journals that I receive, and I haven't personally seen this as a wide-spread issue.  I can think of a couple of cases over my career where the client said they had a microchip and I couldn't find it with my universal scanner.  In those cases I recommended going back to the shelter or vet who implanted the chip and have them scan it with one of their scanners.  I can't say that I ever heard back from those clients to see if the chip was found.

In my own practice I'm a big advocate of microchips, and we use the 134 kHz chips.  We routinely scan new pets, especially any that are brought in as strays.  I can think of at least a half dozen stray pets over my career that I have personally found microchips in and been able to track down the owner.  I can also say that when a client says their pet has a chip and I scan it, I'll find at least 99% of them even if we didn't implant them.  So I believe that as a whole, microchips are very reliable.  Are they perfect and immune to failure?  No.  That's why I tell my clients to still use collars and ID tags, and both of my dogs have this form of identification on them.  But when a collar or tag is lost and the pet gets away, a microchip is still your best chance of having that pet found.

Cindi, I hope this answers the questions your group had on this topic.  There were some comments regarding tattoos as a method of identification, and I'm going to talk about that tomorrow.


  1. I'd recommend scanning any animal with a chip as a part of any wellness visit. Quick and easy way to verify that the chip hasn't migrated. (Recommendation from the JAVMA paper on cats, collars and microchips, sometime in summer 2010, IIRC).

  2. Thanks for bringing that up, Outrider. I forgot to include that uncommonly microchips can move. The standard is to implant them between the shoulder blades, and they're designed to stay in place. However, occasionally they can "migrate", so if the microchip isn't quickly found in the normal place the person scanning should go along the chest, neck, and down the legs just to make sure.

    1. I also have my chips scanned about once a year. Just to make sure. They both are rescue and both groups said they are registered to them. Then they have my name on file. I called the micro chip places and neither chip was registered. Both from different rescue and different micro chip companies. So check that.

  3. An article run by a local news outlet had a much different view of chips and after talking to other vets myself I would disagree with your opinion in that even if the chip hasnt migrated or failed the chances of finding the pet on the multiple databases are not good. Judge for your self....

    "Since mid April they have checked 104 pets. In only 4 cases were they able to scan the chip number, make just one phone call and find the owner's contact information. The other one hundred left them on a logistical leash The sisters had to make multiple calls, visit multiple websites.

    It turns out because there are many microchip makers and so many data bases which store the id numbers it can be hard to figure out which database has the contact information you are looking for."

  4. Thank you for sharing this information.

  5. Dear Dr. Bern: Our wheatie-poo was chipped by Avid in 2007, 6 years ago. When we went to get documentation for a trip overseas, she was scanned by the vet, and nothing was found. We bought our own scanner from Avid, and nothing was found by us either. Avid was absolutely rude and stood by their product, saying chips very rarely die. They offered to have a vet 40 miles away rechip. We're declining and will get her rechipped next year when we try this trip to family again. Taking into account that we'd have to get Molly another rabies shot because of rechipping, and then postpone the trip 21 days, along with repeating the visit to the vet AGAIN 10 days before leaving, we just gave up on it all. If possible, if you have advice about other companies that have chips, I'd appreciate your help. I just hope to never ever deal with Avid again. And thank goodness our little dog didn't wander and needed this chip to locate her for sure. thank you so much

  6. I wrote yesterday about our vet not finding our dog's chip when he scanned her. I used the Avid scanner I just purchased, and it's there, very active and recorded. I copied your post for our vet, along with Avid's brochure giving the frequencies needed to scan successfully so this won't happen to other people.

  7. I do agree that microchip failures are rare, though they certainly do happen. I personally don't like Avid's attitudes over the last several years during the microchip frequency controversies, so I don't recommend their chips, though this is a personal bias. I think Home Again is good, and there are several other smaller companies that also make microchips. If you're going overseas make sure that the chip is ISO compatible, which your vet should be able to tell you.


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