Fig. 1

Fluoroscopic characteristics of each cough grade groups. The proportion of dogs with (A) cervical TBM grade, (B) thoracic-inlet TBM grade, (C) intrathoracic TBM grade, and (D) carinal TBM grade in each cough grade group is demonstrated. In addition, the proportion of presence or absence of (E) bronchial collapse, (F) tracheal kinking, and (G) lung herniation in each cough grade group is demonstrated. The grade of cough are as follows: grade 0, no cough; grade 1, < 3 times a day; and grade 2, ≥ 3 times a day or ≥ 5 min of cough at a time, or severe cough with cyanosis. The TBM grade was evaluated by radiologists based on the percentage reduction in the luminal diameter as follows: grade 1, 0–25%; grade 2, 25–50%; grade 3, 50–75%; and grade 4, > 75%. *The TBM grade of the carinal region increased significantly with the grade of cough (p = .03). Abbreviation: TBM, tracheobronchomalacia