Evaluation of external surgical approaches used for fenestration of the dorsal and ventral conchal bullae in horses: An ex vivo study

Background: Empyema of the conchal bullae, which is a possible additional source of chronic unilateral nasal discharge, affects up to 56% of horses with paranasal sinus disease. Objectives: This study aimed to determine the external surgical approaches for the fenestration of the conchal bullae in horses. Study design: Experimental study. Methods: Six heads of horses were used for external surgical approaches in the maxillary region, and the bilateral ventral and dorsal conchal bullae were fenestrated. Radiographic projections were performed preoperatively, and a further radiographic examination was performed after the surgical procedure using a Steinmann pin inserted through the surgical approach as a radiopaque marker. The approach to the bullae was also assessed by rhinoscopy. Dissection, macroscopic evaluation and digital photographic records of the surgical approaches were performed. Results: A total of 92% (22/24 bullae) of the evaluated conchal bullae were fenestrated. The approach allowed the fenestration of 11/12 dorsal conchal bullae and 11/12 ventral conchal bullae. The postoperative radiographic evaluation allowed identification of the surgical approach and fenestration positioning by observing the location of the radiopaque pin within the conchal bullae. The dissection showed that the surgical approach to the dorsal conchal bulla was 3 cm dorsal to the infraorbital foramen and dorsal to the levator nasolabialis muscle, with no damage to the vascular or neural structures. Main limitation: The surgical approach to the ventral conchal bulla, when performed 1 cm rostral to the infraorbital foramen, was very close to the branches of the infraorbital nerve, which were identified and moved away from the trephination site. This was an ex vivo study and it is possible that nasal haemorrhage would affect the usefulness in clinical cases. Conclusion: The surgical approaches described in this study allow the fenestration of dorsal and ventral conchal bullae in adult horses in a simple way without the need for specific equipment.