Ultrasonography as a diagnostic aid in horses with anaerobic bacterial pleuropneumonia and/or pulmonary abscessation: 27 cases (1984-1986)

The medical records of 83 horses with pleuropneumonia and/or pulmonary abscessation, in which thoracic sonography was used, were reviewed. The sonograms of these horses were reviewed retrospectively for free gas echoes within pleural or abscess fluid. Anaerobic infection was confirmed in 27 horses, and gas echoes were observed in 21 horses. There was a significant (P less than 0.001) correlation between the observation of gas echoes and anaerobic infection in horses with pleuropneumonia and/or pulmonary abscessation. A foul odor to the breath or pleural fluid was significantly (P less than 0.001) associated with anaerobic infection. Poor survival rates were associated with gas echoes or a foul odor to the breath or pleural fluid, both of which were associated with anaerobic infection. Gas echoes within pleural or abscess fluid were found to be a sensitive and specific indicator of anaerobic infection, as was a putrid odor to the breath or pleural fluid. Evaluation for gas echoes and foul odor had better predictive value than did evaluation for gas echoes or foul odor alone. Gas echoes within pleural or abscess fluid is highly suggestive of anaerobic infection. Ultrasonography should be performed repeatedly in horses with pleuropneumonia to assess the progression or resolution of pleural and parenchymal disease. The detection of gas echoes on subsequent ultrasonograms may indicate the development of anaerobic infection.