Incomplete tracheal intussusception in a dog.

An 18-year-old male miniature poodle had a chronic nonproductive cough. On radiographic examination, an opacification resembling a foreign body was noticed within the trachea at the level of the sixth cervical vertebra. When the trachea was examined endoscopically, a circumferential flap-like lesion was found. To differentiate the invagination from an annular mass, thoracic computed tomography (CT) of the trachea was performed. There was cranial displacement and invagination of a tracheal segment creating the flap-like lesion. Tracheal intussusception should be considered as a cause of an annular tracheal mass.