Mouse Ear Tattoo - A Quick and Easy Alternative to Ear Punches and Tags

Oct 13, 2026

Common mouse identification methods—tail/toe tattooing, ear punches, and ear tags—present trade-offs for large or long-term studies, prompting exploration of a faster alternative. Using the Aramis Micro Tattoo system, researchers tattooed numbered dot patterns on mouse ears with a non-toxic ink and a 25 g needle. Animal handling was minimized, and identification speed improved without removing animals. Tattoos remained readable for up to two years with no adverse effects reported.

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Abstract

Introduction

Material and Methods

Results

Discussion

Mouse Ear Tattoo: A Quick and Easy Alternative to Ear Punches and Tags B. Hess Abbott Laboratories, Abbott Park, IL, USA; Abbott Diagnostics – Put Science on Your Side Abstract Some of the more common methods for individual mouse identification include tattooing of the tail or toes, ear punches and ear tags. Each method has its advantages and drawbacks so an alternative method was explored. The Aramis Micro Tattoo system is designed to use a standard hypodermic needle which is re-inked in a well on the opposing side and is commonly used for tattooing the toes of mice. A study was performed to see if this method could be used to tattoo the ears of individual mice using a set pattern for numbering. The micro tattoo equipment, non-toxic ink and a 25 g needle were used to tattoo small dots in a set pattern on the animal ears, giving each a unique number. The animal was gently restrained and the ear punctured the required number of times, excess ink was wiped away and the animals returned to their cages. The ability to quickly identify individual animals and the longevity of the tattoos were monitored over the course of multiple studies. The end result provided an easy method for tattooing and allowed for quick identification of any individual animal. The animals showed no adverse effect and the tattoo pattern has remained readable out to two years. A standard identification chart that is used for toe tattooing can be modified or one created specifically by the user. Acage of up to ten mice can be quickly tattooed, allowing for rapid visual identification without handling the animals. The process has been repeated using hundreds of animals and has produced excellent and reliable results with very little work involved to individually identify the animals. Introduction The various methods of mouse identification each has its own advantages and disadvantages. RFID implants provide a reliable method but the expense may be too high for large groups of animals. Ear tags are cost effective and easy to apply but for long term studies ear tags may be pulled out or lost as a result of fighting or becoming snagged. Tail tattooing is also a widely used method but it requires the technician to have adequate skill to apply the tattoo for long term readability and without injury. Tail tattooing can also bea time consuming process if large numbers of animals are involved. As a result, a quick and easy method to identify mice was developed using a common micro tattoo system normally used for toe tattooing. Material and Methods The Aramis Micro Tattoo system (Braintree Scientific Inc. , Braintree Ma.) is designed for tattooing the toes of mice. The tattoo apparatus consists of a forceps like device with a magnifying glass attached (Figure 1 ) . A 25g hypodermic needle is passed through a hole and screwed in, the needle than passes through a hole on the opposing side into an inkwell. The ink consists of a non-toxic paste that can be squeezed into the ink well. A pipette tip can be cut down and used as the ink well to aid in cleanup and provide a larger repository for ink for use in multiple animals. Our studies commonly involved 10-20 Balb/C mice housed 5 per cage on a micro isolator rack system. The mice are part of amonoclonal development program and some animals maybe housed for extended periods of time, sometimes as long as 18-24 months. A numbering system was developed (Figure 2) using a simple dot pattern for identification of individual animals. The mice were tattooed following a pre-bleed during which the animals were anesthetized using sevoflourane. The anesthesia was helpful during the tattooing, but is not a requirement. The animals were gently restrained by scruffing the back of the neck and the needle is passed through the ear the required number of times, the needle is re-inked after passing into the ink well on the opposing side. Any excess ink is gently wiped off using adamp gauze pad and the animals are returned to th

FAQs

What identification methods were compared, and why was an alternative needed?

The work references tail/toe tattooing, ear punches, and ear tags, noting drawbacks such as cost for RFID and the risk of tags being lost or pulled out. A quick alternative was therefore explored for individual mouse identification.

How does the Aramis Micro Tattoo method number mouse ears?

A 25 g hypodermic needle is used in the Aramis Micro Tattoo system to apply small dots in a predefined pattern to the ear, using non-toxic ink. The needle is re-inked as needed, excess ink is wiped off, and animals are returned to their cages.

How long did the ear tattoos remain readable, and were there adverse effects?

The study reports that the tattoo pattern stayed readable out to two years and that animals showed no adverse effect. Discomfort was minimal and ear blood flow appeared unaffected.

Oct 13, 2026

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