A Technique for Examining the External Ear Canal in Standing Sedated Horses

Abstract

In this study ultrasonography, local anesthesia, and endoscopy were performed in both ears of 23 horses. The aim was to find a reliable technique for examination of the external ear canal in standing sedated horses and to create a grading of debris and the occurrence of abnormalities in clinically healthy horses. Local blockage of the great and internal auricular nerves was performed after caudal palpation at the base of the ear and ultrasonographic assessment of the styloid process of the auricle as a reference point for the needle placement. The otoscopic examination was accomplished with two flexible video endoscopes with 2- and 7-mm tip diameters. The depth of the styloid process varied ultrasonographically from 2.08 to 2.73 cm on the left side and from 2.04 to 2.76 cm on the right side. Local anesthesia was successful in all sedated horses, without any long-term complications. The grading of endoscopic appearance of the skin, epithelium, and ceruminous and cell debris in the cartilaginous and osseous part including tympanic membrane of the equine external ear canal ranged from I to III. Abnormalities like osteoma, granuloma, hemorrhagic or erythematous areas, and narrowing of the osseous part of the external ear canal due to stenosis (exostosis) were seen in 10 of 23 horses. The tympanic membrane was visualized in 20 of 23 horses. Local blockage of the great and internal auricular nerves was found to be a reliable method for equine ear anesthesia.