Radiography of external ear canal and tympanic bullae in dogs

Radiography of the external ear canal and tympanic bulla can provide information on the integrity of the external ear canal and middle ear. For complete clinical diagnosis of otitis externa and otitis media, at least two views should be taken. The rostrocaudal lateral oblique view gives excellent details of both tympanic bullae in one exposure; however the difficulty in positioning the patient is a constraint that has to be taken care of. The dorsoventral view provides excellent visualization of external ear canal, but due to superimposition of pterosal part of the temporal bone over the tympanic bullae it makes it difficult to evaluate the bullae properly. The positive contrast canalography aids in evaluating the diameter of external ear canal, stenosis and narrowing in the external ear canal, and integrity of the tympanic membrane.