An ear tag is a small metal clip with an individual number that may be stamped, stamped and painted, or etched. Stamped numbers may have three or six digits. The 6-digit numbers extend on both sides of the clip. Laser-etched digits are more compressed than stamped numbers, so that more characters can fit on each side of the tag. Metal tags are preferred over plastic tags because they are more durable and less prone to chewing by cage-mates. Nevertheless, the tag can be lost during grooming, fighting, or even infection of the site.
The ear tag has a sharp point. When the tag is pressed by the applicator, the tag point is pushed through both the ear and the hole side of the tag. Practice first on a tag to be sure that you can place it properly in the applicator. Note that the hole side of the tag is held flat against the jaw of the applicator that has the larger indentation. When placed correctly in the applicator, the tag point is bent, or crimped, as it passes through the hole.
Applying a tag is quick and causes the animal minimal pain. However, due to the weight of the ear tag, mice are ear-tagged at weaning or older. It can be done with the animal conscious, although anesthesia is preferable, especially with the fast-acting gaseous anesthetic agents that are available.
- Soak the ear tag in alcohol or another disinfectant before use.
- Insert the ear tag into the applicator jaws, keeping the hole side of the tag flat against the jaw with the larger indentation.
- Place the tag at the base of the ear proximal to a ring of cartilage. The cartilage will anchor the tag, minimizing the chance of it being ripped out of the ear later.
- After squeezing the applicator, check that the tag point has come through the hole and is crimped. This action seals the tag and locks it in the ear.
Information from the AALAS Learning Library