Rat Ear Reattachment as an Animal Model

The external ear of the rat is an excellent model for practicing microsurgical dissection and for the refinement of microvascular anastomoses, techniques that are crucial for microvascular en bloc tissue transfer and replantation. Preparation of the rat ear for replantation requires familiarity with the vascular anatomy and gentle tissue handling with atraumatic dissection of arterial and venous pedicles, steps similarly crucial in raising free flaps for microvascular transfer. The strategy of performing accurate reduction and stabilization of the tubal cartilage prior to vessel repairs, anastomosing the more deeply seated external carotid artery prior to the more superficial posterior facial vein, is as critical to rat ear replantation as for digital reattachment. In addition, the rat ear as compared to other animal models such as the rabbit ear or canine hindlimbs is much less expensive. Compared to the rat hindlimb model, rat ears are much easier to observe, which is a distinct advantage when used as a model for long-term study of replantation, revascularization, or transplantation.