To make a "chip" communicate with a reader (scanner) contactlessly, technology known as RFID (Radio Frequency Identification) is used. This permits contactless dialogue between the "chip" and the "scanner" using radio waves from the chip which receives power from the scanner. In the case of the identification of domestic animals, low frequencies are used.

Between 1986 and 1996 there were several 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 method which made the microchips and the readers, also known as "scanners", compatible. 

Worldwide, many animals had been "chipped" with transponders before the standard was published. These 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). Given the life span of domestic animals and the adoption of the ISO standard by many countries it is likely that before long these non-standard chips will only be a memory.

The chips which conform to ISO11784 are called FDXB, FDXA and HDX. For reasons of size, only FDXA and B chips can be injected into domestic animals. HDX chips are used mainly in animal husbandry, generally used in ear tags.

Some countries still have not 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.

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.

Because of the diversity of chips and their different modes of operation, some models of chip cannot be read by some of the currently available readers. The Realtrace, PetScan V8, and the Halo will read A & B, while the Universal Scanner will read all chips used in animals worldwide.

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:

However, this regulation is changing.
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

ICAR (International Committee for Animal Recording) is an international body whose responsibilities include checking that RFID products offered by companies (manufacturers and distributors) comply with ISO standard 11784/85. This body issues a manufacturer code after the product has been checked by an approved laboratory. Trovan's manufacturer code is 956, RealTrace (in France) use 936.. This can be used at the beginning of the chip’s code instead of a country code, or it can follow it.

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 French law in 2003.
3 digits    2 digits    2 digits    8 digits
250        26         XX        XXXXXXXX
- 250 is the ISO country code for France, Great Britain is 826.
- 26 is the species code, in accordance with the Ministry of Agriculture’s coding definitions.
26 = domestic carnivores 25 = equines 22 = exotic pets and wild animals
- the next two digits are the manufacturer number assigned by the Ministry of Agriculture.

This is a complex system and is useful but the complexity increases costs.

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 by connecting to the database

There are some concerns about the 900... prefix, this is a default code used by multiple manufacturers and traceability has proved to be an issue for more informaation on this click here).

However, you will have either direct information on the animal's country of origin (if the chip includes the country code) or indirect information through "europetnet" (if the first three digits indicate the manufacturer and they have transmitted the information to Europetnet).

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

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