Validation of an Ultrasound Imaging Technique of the Tympanic Bullae for the Diagnosis of Otitis Media in Calves

BACKGROUND Otitis media is a common disease in calves that can be subclinical, making antemortem on-farm diagnosis challenging. OBJECTIVES To evaluate the sensitivity and specificity of ultrasonography of tympanic bullae for the diagnosis of clinical and subclinical otitis media and to evaluate the reproducibility of the technique. ANIMALS Forty calves 19-50 days of age were selected from a veal calf farm. METHODS Prospective study. Ultrasonography was first performed on the farm by ultrasonographer A (US A). Ultrasonography was repeated by ultrasonographer A (US A') and another ultrasonographer (US B) at the Centre Hospitalier Universitaire Vétérinaire. Images were later reread by both examiners and a diagnosis was recorded. The calves were euthanized and submitted for necropsy, and histopathologic diagnosis was used as the gold standard. RESULTS Forty-five bullae were affected by otitis media and 35 bullae were normal. Sensitivity and specificity of the ultrasound technique ranged from 32 to 63% and 84 to 100%, respectively, depending on the examiner and classification of suspicious ultrasonography results. Kappa analysis to evaluate interobserver agreement between A' and B yielded a к value of 0.53. Agreement within the same examiner (A versus A') yielded a к value of 0.48, and real-time ultrasound versus rereading of recorded images for A' and B yielded к values of 0.58 and 0.75, respectively. CONCLUSIONS Sensitivity and specificity of the ultrasound imaging technique are, respectively, low and high for diagnosis of clinical and subclinical otitis media in calves, with moderate reproducibility.