Tympanic bullae ultrasonography is feasible in nonsedated healthy rabbits (Oryctolagus cuniculus).

Objective: To assess the feasibility of ultrasonography of the tympanic bullae (TB) in live, nonsedated rabbits (Oryctolagus cuniculus).

Animals: 40 healthy rabbits undergoing TB ultrasonography without sedation between September 2021 and May 2022.

Procedures: For each rabbit, fur was clipped over an area (3 X 3 cm) at the level of the angular process of each mandible, then 3 ultrasonographic planes of each TB were imaged via ventral approach, with measurement of the time taken to complete the examination. Three items were assessed for each plane: TB depth, wall integrity, and contents (present or absent). Results were compared for rabbits grouped as standard-sized breed type versus dwarf-sized breed type.

Results: The examination could be carried out successfully in 36 of 40 (90%) of rabbits with clipping. The restraint and examination were relatively well tolerated by the animals, except for the transverse sections. Obtaining oblique and longitudinal sections, carried out on 33 of 40 (83%) rabbits in our study, allowed for evaluation of the TB. The examination was feasible with all rabbit sizes. The depth of the TB was found to be linked to the size of the rabbit and especially to the size of its jaw. Visualization of the distal bulla wall was observed in 2 of the 40 (5%) subjects, consistent with abnormal fluid contents or bulla osteitis.

Clinical Relevance: Ultrasonography of the TB was easy to learn and rapid to perform, with a mean examination time of < 10 minutes (mean of 8.71 minutes) without any sedation.