Should My Pets have a Microchip?

Microchips have been widely used in the USA for returning pets to their rightful owners when lost. In much of the rest of the world, they also act as the definitive identification for each pet.

Microchips first came to light in 1980’s with Home Again when I was working at a veterinary office.  Microchips are a small unit about the size of a grain of rice, inserted under the skin with a needle.  This  Wikipedia article  explains how they work and the history of chips.  Basically they work as an RFID (Radio Frequency Identification) device, that uses a passive electromagnetic field, which can be scanned and read with a hand held device.

Microchips do not hurt a pet, other than the quick injection under the skin to place them. This sounds relatively easy, but I have seen chips go missing when they were not injected all the way under the skin, and would apparently fall out at some point.

Microchips are used not only used for dogs and cats, but also many farm animals, birds and even tortoises.  They replace ear tags, which can be lost or removed.  In dogs and cats, the standard international location for placement is the center (mid-line) of the back, on the neck or between the shoulder blades.  For birds, common placement is on the breast, and in horses, the left side of the mane, an inch below the main in the mid-line of the mane.

Some of the early microchips in dogs and cats would migrate around the body under the skin, instead of staying in place at the back of the neck.  Occasionally we would scan a pet a find the chip down near a elbow or down the side of the neck or shoulder.  New technology has helped alleviate this.

While many shelters and animal control officers can now scan and read microchips, as well as a veterinary office, having the identification number does no good unless the chip is registered so the owner can be identified and notified.  There is no one main registry for chips, and therefore even with a verifiable chip number it can still be hard to track down the owner.

Internationally, microchips are used more for identification than for a lost pet.  Several countries make microchipping mandatory, and they  use the chip number for dog licenses.  Upon arrival into Europe, for instance, there is a veterinary check upon arrival, the microchip is scanned and must match as the number printed on all the pet documents.  Many countries in the world do this.

In the rest of the world, a 15 digit international ISO microchip is the norm, but here in the United States there are 3 other chip standards in  use as well as the ISO compliant chips.

  • The Trovan Unique chip was in use in the 1990’s but has pretty much fallen out of use.
  • The Destron chip is  used under the Home Again,  & 24 Petwatch brands, with  10 digit alpha-numeric identification number.
  • Avid Friendship chips, which are encrypted different and can be hard to read with standard scanners.

The 15 digit ISO compliant microchips are now used by most veterinarians, and are the suggested chip for any international travel. Hong Kong, however, refers the 9 digit numeric original AVID chip, and will re-chip a dog upon entry to that country if another type of chip is present.

If you travel, and if your pet has more than one microchip, be sure to put all the microchips numbers on all the documents.  You don’t want to be in a position of having only one number scanned, and having it be the wrong one not on paperwork.

Even if your pet never travels, a microchip is still a good form of identification.  As all the chip companies will tell you, a tag can come off a collar, or the collar can come off the pet.  Just remember to register the microchip number with the manufacturer, and with any of the lost pet microchip registry out there like:

or any of the other microchip registry websites.  The more places your pets microchip is registered, the easier it would be for someone to find you and get your pet back to you.  Unfortunately there are plenty of pets out there with a microchip unregistered, so even if the shelter or animal control officer scans and finds the chip, there is no way to find the owner.  Don’t let this happen to you.