Radiographic identification of the equine dorsal and ventral nasal conchal bullae

Summary The recent understanding that pathology of the nasal dorsal (DCB) and ventral (VCB) conchal bullae can be a common and underdiagnosed cause of unilateral nasal discharge in horses, has generated new interest in these structures. The normal computed tomographic anatomy of the bullae has been described in detail; however, computed tomography facilities are still limited to referral centres, and radiography remains the primary diagnostic imaging modality for most equine practitioners. The purpose of this descriptive imaging study was to describe the radiographic anatomy and limits of both DCB and VCB in equine cadaver skulls. The heads of 10 horses (7 horses, 3 ponies) of unknown age were transected sagittally in the midline, and five radiographic projections (left and right laterolateral, left and right latero30°dorsal–lateroventral oblique and dorsoventral) of the sinuses and nasal cavities were obtained, before and after the placement of stainless steel wire moulded inside the bullae. The radiographic appearance of the VCB and DCB was evaluated on both plain and wire radiographs, assessing their anatomical limits in relation to the cheek teeth and describing the variations related to age and type of horse. The radiographs allowed correct identification of the rostral and caudal limits of the DCB and of the rostral limit of the VCB in the majority of the horse heads. Mild variations in the radiographic appearance of the bullae between horse and pony heads were noted. The laterolateral projections resulted in the best visualisation of the bullae in all the heads used in the study. This study showed that the VCB and DCB are radiographically identifiable on plain radiographs in most mature horses, and that pathology of these structures may be identifiable using radiography.