Ultrasonography showing the retropharyngeal mass. The scan was performed from the left side of the cow, with the probe in a transverse position; the trachea and epiglottic cartilage present as landmarks. A mass can be identified on the dorsal surface of the arytenoid cartilage. Cr: cranial; Cd: caudal; Ac: arytenoid cartilage; Tr: trachea area; ※: mass.