Comparison of computed tomography and routine radiography of the tympanic bullae in the diagnosis of otitis media in the calf.

BACKGROUND: Otitis media is difficult to diagnose antemortem. Case reports have described computed tomography (CT) in the diagnosis, but not all cases were confirmed. HYPOTHESIS: CT is a sensitive and specific imaging modality of the tympanic bullae and can be used as the gold standard for the diagnosis of otitis media. ANIMALS: Sixteen Holstein calves 5-7 weeks of age were included.
METHODS: Prospective study. All calves were sedated with i.v. xylazine (0.05-0.15 mg/kg) for routine radiography (3 views) and CT of the tympanic bullae followed by necropsy.
RESULTS: Based upon necropsy findings, 10 of 16 calves were affected with otitis media, 4 unilaterally and 6 bilaterally. Imaging changes associated with otitis media included increased soft tissue opacity within the bulla, thickening of the bulla wall, enlarged bulla, and osteolysis of the bulla wall and trabeculations. The most frequent radiographic changes were lysis of trabeculations and increased soft tissue opacity, which were present in 56.3% of affected bullae. On CT, increased soft tissue opacity within the bulla was present in 93.8% of affected bullae. Sensitivity of radiography and CT was 68.8 and 93.8% and specificity was 50 and 100%, respectively. The κ value between radiography and CT with necropsy diagnosis was 0.19 for radiography, indicating poor agreement, and 0.94 for CT, indicating excellent agreement.
CONCLUSION: CT is more specific, more sensitive, and easier to interpret than radiography and can be used as the gold standard in the diagnosis of otitis media in the calf.