Are your pets microchipped? My dogs are. But I’ll be honest and tell you that I've implanted ther chips with an expectation that their low-tech tags will speak louder than their hardware in a “lost and found” situation. The microchip is mere back-up. But in the event my dogs’ collars should somehow lose their way as well, I can always hope the microchip will help them get back home.

I rely on this technology along with millions of pet owners all over the world. But the vagaries of shelter and veterinary hospital management being what they are, I sometimes wonder whether my lost dogs would ever get treated to the business end of a microchip scanner (the device we use to "read" the chips).

To make matters worse, the application of any technology must factor in its technical fallibility. Nothing’s perfect, we rationally comprehend. But when it comes to the magic of TV, radio, computers and microchips, we too often assume the product is very nearly foolproof.

Not so in the real world when it comes to microchip identification for pets. Otherwise, why would we need a “scan-off”?

Let me explain: Last month’s JAVMA (Journal of the American Veterinary Medical Association) effectively tipped its hat to the notion of a microchip scanner “scan-off” when it included two papers from a microchip research team in its end-of-year issue.

The goal of this research was to determine the sensitivity of the scanners used to detect and read the commercially available microchips used in pet identification. These studies were deemed important so that veterinarians and shelters could determine whether their efforts in implanting and scanning patients and foundlings were as effective as the microchip manufacturers claimed.

The first paper looked at the “in vitro” sensitivity of a variety of scanners to a range of microchips in a controlled setting. The second examined scanners for sensitivity in a more real-world situation, using almost 4,000 shelter pets from six different facilities to determine their relative efficacy in a real pet identification scenario.

This team, led by Ohio State researchers, also included representatives (read: presumed commercial backing) from microchip manufacturers Bayer (resQ microchip), Trovan (AKC-CAR microchip) and Schering-Plough (HomeAgain microchip). I assume industry heavy, Avid, declined to participate (but I may be wrong).

Here’s where some background information might be useful: The microchip ID industry for pets in the US has a relatively short lifespan. Ten years ago few pets received microchips to aid in their identification. Today, most shelters require microchipping for the animals that pass through their doors, while veterinarians strongly recommend their implantation. That’s because only 30% of dogs and 2-5% of cats remanded to shelters find their way home again.

There are three different kinds of technologies used for microchips. These rely on three different frequencies. But microchipping your pet is not as easy as 1-2-3. That’s because your shelter or veterinarian may be using a different standard of microchip than the next facility down the street. So if you select one brand of microchip it may be that the microchip scanner (or “reader”) your local shelter uses is not compatible with the microchip your vet has implanted.

Here's some background on this from a controversial past series of posts on the "microchip wars": post 1, post 2 and post 3.

To solve this complex problem and help more pets get back home, a uniform standard for microchip frequencies was proposed by a broad based animal welfare coalition…and subsequently declined by some manufacturers (most notably by Avid, the company with the largest market share and the most to lose from a uniform microchip standard).

Because the US’s microchip companies could not be made to agree to the uniform standard used in the rest of the world (134.2 kHz, or “ISO standard”), the “universal scanner” was devised. This scanner would be capable of reading all microchip frequencies. Every company that manufactures microchips now also manufactures universal scanners…except Avid.

But it seems that not all scanners are created equal. Some are better than others at reading a wide variety of microchips. That means your pet may get lost, found, scanned and euthanized if the scanner comes up “empty.”

Three universal scanners are available which purport to read all three microchip frequencies. Avid offers one with universality limited to its own frequency (125 kHz). But none came close enough to perfection to meet the average pet owner's expectations, if mine are any guide.

For the real world, in-shelter test, here are the chips, scanners and their results:


  • Avid makes Friendchip, an encrypted 125 kHz microchip.
  • HomeAgain makes a Schering-Plough distributed, unencrypted 125 kHz microchip
  • 24PetWatch is an unencrypted 125 kHz microchip made by Allflex (a newcomer?)
  • AKC-CAR is a 128 kHz microchip made by Trovan
  • ResQ is a 134.2 kHz microchip made by Bayer
  • HomeAgain also makes a 134.2 kHz microchip distributed by Schering-Plough


  • Bayer: For detecting and reading 125 kHz encrypted and unencrypted), 128 kHz and 134.2 kHz microchips.
  • HomeAgain: Same as Bayer’s detecting and reading mix.
  • AKC-CAR: For detecting all three frequencies but can only actually read the 125 kHz and 128 kHz varieties.
  • Avid: This 125 kHz scanner can detect and reading all encrypted and unencrypted chips at this frequency. It is not a universal scanner.

Results (in a nutshell):

  • HomeAgain’s scanner won for overall sensitivity at 93.6 to 98.4% across all six microchip types.
  • The Bayer scanner did next best at over 97% for four chips but only about 90% for the more popular 125 kHz chips.
  • AKC-CAR’s did over 95% for the 128 and 134.2 kHz chips but lost big at 66-75% for the 125 kHz chips.
  • Avid scored as well as HomeAgain on the one frequency it could read, at >97%.

Interestingly, none of the scanners had a 100% sensitivity for any kind of microchip, including for the one of its own company’s design.

In addition to helping us all recognize the extremes of our human imperfections, this study made some additional points on scanners I couldn’t help but relay. Because they recognize that technology is further limited by humans who use it, the researchers included a section on how to properly use a scanner and which pets are most likely to require more diligent scanning.

And here’s a big discovery (at least for me): Believe it or not, weight is a big factor in microchip detection. For each 5-pound increase in body weight, the odds that a 125 kHz chip would be missed increases by 5%—by 8% for other frequencies. Bigger pets, then, need more assiduous scanning than others.


Overall, I was as impressed with the design of the study as I was by its results. (The researchers busted their butts on this one.) I also have to commend the microchip manufacturers who participated in this study. It takes an impressive commitment to corporate transparency to participate in or fund a study whose results may not be to your liking. Kudos.

As to the microchip industry and its scanning problems…it’s clear that perfection would improve my chances of relying comfortably on my dogs’ microchips. But given that I still expect the big factor in their microchip detection to come down to whether the scanner gets used at all or not, I can live with the relatively small possibility of scanner error.

This conclusion, of course, presumes that shelters and veterinarians will read this study and choose to use HomeAgain’s universal scanners on all their pets—for now, anyway…until the next study tells us how much better the industry’s doing…or so we can only hope.