Skip to main content


Recent Advances in Microchips for Companion Animals

Each year, millions of dogs and cats enter animal shelters in the United States, with most of these animals lacking any type of identification. The Humane Society of the United States estimates that only 30% of dogs and 2% to 5% of cats that enter animal shelters are returned to their owners each year. One potential method for improving these reunification rates would be to increase the use of microchipping, which provides a permanent and unalterable method for identifying pets.

Sensitivity of commercial scanners to microchips of various frequencies

Throughout much of the world, a standard recommended by the International Organization for Standards that 134.2 kHz microchips be used for microchip identification of companion animals has been adopted as the preferred or sole standard. This standard has been endorsed by groups such as the American Veterinary Medical Association, the American Animal Hospital Association, the Humane Society of the United States, the American Society for the Prevention of Cruelty to Animals, and the Society of Animal Welfare Administrators, as well as the National Standards Institute. In the United States, however, a national standard for microchip identification of companion animals does not currently exist. However, the majority of microchips in the United States function at 125 kHz and there are three distinct frequencies in the U.S. with the 125 kHz, 128 kHz and 134.2 kHz all being used.

In recent years, several universal scanners that purportedly can detect or read microchips of all 3 frequencies used in the United States have been introduced. However, there has been growing concern that some of these newer universal scanners may not be able to reliably detect or read certain microchips. The purpose of the studies reported here, therefore, was to evaluate sensitivity of 4 commercially available microchip scanners used to detect or read encrypted and unencrypted 125 kHz microchips, 128 kHz microchips, and 134.2 kHz microchips under controlled conditions and in a field setting in animal shelters.

JAVMA Study Results

Summary Information

  • {{IconPDF}} Summary of Study Findings
  • Plan for a Happy Reunion: This brochure {{IconPDF}} offers helpful information for pet owners on the importance of pet identification to keep pets safe. In addition, there is a checklist for pet owners offering suggestions and actions if their pet becomes lost. It is designed for use in puppy and kitten packages, as well distribution during wellness examinations.

Additional Articles