Chylothorax associated with tricuspid dysplasia and atrial septal defect in a bullmastiff

Transudate pleural effusion associated with tricuspid dysplasia and ostium secundum-type atrial septal defect was diagnosed in a 14-month-old bullmastiff. Following administration of furosemide and an angiotensin-converting enzyme (ACE) inhibitor, the dog remained free of pleural effusion for 10 months, until he showed severe dyspnea due to chylothorax. Medical therapy was unsuccessful to avoid recurrence of life-threatening pleural chylous effusion. Ligation of the thoracic duct and apposition of an omental pedicle flap were effective in the resolution of pleural chylous leakage.