An unusual complication of ear punching in a laboratory mouse

Abstract

AbstractEar punching and notching are common methods of identification of laboratory rodents. Concerns have been raised regarding pain and discomfort, infection, thermoregulation and tearing. However, the evidence regarding these potential adverse events is currently limited. In this case report, we describe an unusual complication of ear punching in a laboratory mouse. The mouse had its left ear punched with a single hole at 3 weeks of age. At 11 weeks of age, the mouse caught its left foreleg through its left ear punch up to the level of the shoulder. The mouse's leg was released and the pinna cut to form a notch rather than a hole. To avoid this situation, we suggest that an ear notch be considered rather than an ear punch. This case also highlights the value of daily checks to ensure that the risk of any adverse effects from such unpredictable events is minimised.