Significance of incidentally identified bullae and blebs on thoracic computed tomography and prevalence of subsequent pneumothorax in dogs.

Objective: To determine the prevalence of incidentally found pulmonary bullae and blebs (PBBs) in a population of dogs undergoing thoracic computed tomography (CT) for reasons other than presence of pneumothorax and to determine the prevalence of subsequent spontaneous pneumothorax (SP) development.

Study design: Retrospective study.

Animals: A total of 30 dogs.

Method: A total of 2221 CT studies of the sample population were retrospectively assessed for the presence of incidental PBBs between April 2013 and April 2019. Inclusion criteria were complete thoracic CT studies from dogs obtained from the hospital database. Exclusion criteria were concurrent presence of a pneumothorax or severe pulmonary disease preventing assessment for PBBs, an air-filled space related to a pathological process, for example, neoplasm, incomplete CT studies, or no available follow-up. Long term outcome was evaluated using a questionnaire to determine the occurrence of SP post CT examination.

Results: Incidental PBBs were identified in 30 out of 2178 (1.4%) CT studies that met the inclusion criteria. None of the dogs subsequently developed clinical evidence of SP (median follow-up time 1255 days, range: 147 to 2363 days). One dog died suddenly of unknown cause and as no post-mortem was performed SP could not be ruled out.

Conclusion: There was a low prevalence of incidentally found PBBs in dogs. None of the dogs followed over a long period subsequently developed SP.

Clinical significance: Based on this study, prophylactic removal of lung tissue containing incidentally found PPBs is not justified.