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Interpretation of transponder chip implant codes for pets, horses and exotic pets.

Some technical information…

For contactless communication in-between a “chip” and a reader (scanner), technology known as RFID (Radio Frequency Identification) must be used. This permits contactless dialogue between the “chip” and the “scanner” using radio waves. The performance and thus the applications are different according to the frequencies used. In the case of the identification of domestic animals, low frequencies are used.

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Some history…

Between 1986 and 1996 there were a few miniaturized transponders (chips) available on the world market which could be injected into animals. Although they all used the technology known as RFID (Radio Frequency IDentification), they were not mutually compatible. Standardization under ISO 11784 and 11785 in 1996 imposed an operating mode which made the transponders and readers, also known as “scanners”, compatible.

Worldwide, many animals had been “chipped” before the standard was published, these transponders did not conform to the current standard, as defined by ISO 11784/85. These non-ISO standard “chips” operate at frequencies outside of that defined by the 1996 ISO standard (134.2kHz).

The chips which conform to ISO11784 are called FDXB, FDXA and HDX. For size matters, only FDXA and B chips can be injected into domestic animals. HDX chips are used mainly on livestock, generally integrated into ear tags. Some countries have not yet imposed the FDX B standard and continue to use the FDX A type chips (North America, Australia, Taiwan …). In Europe, all countries use chips which comply with the ISO FDX B standard.

Because of the diversity of chips and their different operating modes, some chip models cannot be read by some of the currently available readers. The readers designed by Realtrace, V8, RT250 and V8M read FDX A and B, EM4102 chips; and for the first two models, HDX and EM4102 chips (mainly used in access controls).

In light of the above you may encounter an animal carrying a microchip whose coding (the identification number registered in the chip and displayed by the reader) does not correspond to the ISO standard.


The following notes should enable you to accurately determine the type of chip injected into the animal and to interpret the data, if they comply with the ISO standard i.e. have 15 digits.

* If the chip number consists of 10 digits and letters: 

This is an FDXA chip.

* If the chip number consists of 15 digits: 

This is an ISO chip (FDXB).

As for the chip number’s structure, under the ISO it was originally intended that the first three digits would correspond to the international country code:

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However, this regulation has evolved.

For example, Great Britain (country code 826) has abandoned its initial coding and has decided to provide vets with chips coded as follows:

3 digits
12 digits
The animal's unique identifiation number

ICAR (International Committee for Animal Recording) is an international organisation whose responsibilities include checking that RFID products offered by companies (manufacturers and distributors) comply with ISO standard 11784/85. This organisation issues a manufacturer code after the product has been checked by an approved laboratory. RealTrace / Atria’s ICAR manufacturer code is 939. It can be used at the beginning of the chip’s code or after the country code.

Example :

Chip for Chile or Mexico: 939 XXXXXXXXXXXX

Chip for Switzerland: 7560939 XXXXXXXX


In France, the chip coding definition conforms with the ISO standard and was imposed by decree in 2003.

3 digits
2 digits
2 digits
8 digits

250 is the ISO country code for France 

26 is the species code, in accordance with the Ministry of Agriculture’s coding standard.

26 = domestic carnivores25 = equines22 = exotic pets and wild animals

the next two digits are the manufacturer number assigned by the Ministry of Agriculture.


When looking at a chip number we recommend that you:

* Read the first three digits.

  • If the number made by the first three digits is between 900 and 985, this is not the country code but the manufacturer code issued by ICAR.

  • If the number is below 900, it is probably the country code.


Finally, please note that you can obtain information on chips other than those used in France (code 250) by connecting to the database:

To find the owner of a dog found in France you can contact the ICAD company: Tel: 0810 778 778


WARNING: analysing the code will not always allow you to find the dog’s owner or the vet who implanted the chip. In some cases, you will need to contact the chip manufacturer (ICAR code) to find the distributor in that country. They should be able to tell you to whom the chip was sold.

However, you will obtain direct information on the animal’s country of origin (if the chip includes the country code) or indirectly through “europetnet” (if the first three digits indicate the manufacturer and they have transmitted the information to Europetnet).

From September 2013, it has been possible to register additional data in the chip. Including the telephone number of the database manager and/or the phone number and email of the pet owner, if the owner has given consent to the vet during the implant of the transponder.

Only the new generation of readers, V8, RT250 and V8M allow this additional information to be read.

What the law says about identification:

Identification of domestic animals is a regulatory obligation. This rule has gradually been extended to all domestic carnivores (dog, cat, ferret).

 –  in France:

Under the laws of January 6, 1999 and May 17, 2011, identification of dogs and cats is compulsory for:

  • all transfers (sale or gift)
  • all dogs older than four months born after January 1999
  • all cats older than 7 months, born after 1 January 2012

–  in Europe 

The electronic transponder is now essential for any animal moving within the European Union.