Computed tomographic findings in 205 dogs with clinical signs compatible with middle ear disease: a retrospective study.

Abstract

Computed tomography (CT) is considered to be the reference method to evaluate middle ear structures. To evaluate the presence and severity of CT changes in the middle ear and establish if any specific clinical presentations are associated with otitis media. Medical records of animals referred for CT with history and clinical signs consistent with middle ear disease. Retrospective evaluation of CT examinations of tympanic bullae performed over a six year period. Medical records were reviewed for signalment, clinical signs and cytological evaluation of the external ear canal. Dogs were divided into three clinical groups: chronic otitis externa (Group 1), peripheral vestibular disorder (Group 2) and other clinical presentations (Group 3). Group 1 - Of 214 ears, 87 (40.7%) had CT abnormalities: 38 of 87 (17.7%) had material-filled bullae, 42 of 87 (19.6%) had thickened bullae walls and seven of 87 (3.2%) had lysis of the bulla. Abnormalities were significantly more frequent in dogs with suppurative otitis than in erythemato-ceruminous otitis (57% and 23%, respectively; P=0.003). Proliferative otitis, particularly in French bulldogs, was associated with severe otitis media. Group 2 - Of the 106 ears, 91 (85.8%) had normal tympanic bullae. Group 3 - Of the 26 ears from deaf dogs, 17 had filled bullae; all nine affected dogs were Cavalier King Charles spaniels. All dogs with Claude Bernard Horner syndrome or head tilt had normal tympanic bullae. CT is useful for canine chronic otitis externa, particularly in suppurative or proliferative otitis, even in the absence of associated neurological signs.