NVAP Reference Guide: Animal Identification

Last Modified: March 20, 2024

To control and eradicate animal diseases, epidemiologists must be able to trace the movement of animals. This goal can be realized only if the animals are properly identified and the individual and the herd, flock, or group identification are recorded. Requirements for official identification of livestock are defined in title 9 of the Code of  Federal Regulations (9 CFR), Part 86, Animal Disease Traceability.

As an accredited veterinarian, you are legally responsible for properly identifying animals and recording the identification on certain official documents, such as CVIs, test charts, and vaccination charts. It is essential that another individual be able to positively identify animals that you have listed on official documents. When documents require animal identification, record all forms of identification associated with the animal.

Acceptable means of identifying different species of animals are defined below.  Official eartags (2.19 MB) are used for several species. The design, size, shape, color, and other  characteristics of the official eartag will depend on the needs of the users, subject to the approval of the Administrator. The official eartag must be tamper-resistant and have a high retention rate in the animal. Official eartags must adhere to one of the following numbering systems:

  1. National Uniform Eartagging System (NUES). A numbering system for the official identification of individual animals in the United States that provides a nationally unique identification number for each animal. The first two numbers on a tag are the numbers assigned to a specific State. See tables 4 and 5 for assigned State numbers.
  2. Animal identification number (AIN). A numbering system for the official identification of individual animals in the United States providing a nationally unique identification number for each animal. The AIN contains 15 digits, with the first 3 being the country code (840 for the United States), the alpha characters USA, or the numeric code assigned to the manufacturer of the identification device by the International Committee on Animal Recording. The AIN beginning with the 840 prefix may be used only on animals born in the United States. An official eartag which contains or displays an AIN with an 840 prefix must bear the U.S. shield.
  3. Premises-based number system. The premises-based number system combines an official premises identification number (PIN), as defined in this section, with a producer's livestock production numbering system to provide a unique identification number. The PIN and the production number must both appear on the official tag.
  4. Any other numbering system approved by the Administrator for the identification of animals in commerce. 

View a complete listing of Official Eartags (882.33 KB). (882.33 KB) USDA-approved backtags cannot be used as the only identification for on farm testing or for movement other than in slaughter channels. For the purposes of identifying animals, a Premises Identification Number (PIN) is a unique number assigned by a Federal or State animal health official to a livestock production unit that is, in the judgment of the SAHO or Assistant District Director, epidemiologically distinct from other livestock production units.