Imaging diagnosis: pneumothorax and focal peritonitis in a dog due to migration of an inhaled grass awn.

A 1-year-old working Kelpie developed pneumothorax and focal peritonitis after inhalation of a grass awn that migrated from the lung, through the diaphragm, into the peritoneal cavity. Radiographic evidence of sternal lymph node enlargement was fundamental in the diagnosis of intraperitoneal disease and prompted abdominal ultrasound leading to definitive diagnosis.