Fluoroscopic characterization of pectus excavatum in dogs: a cross-sectional study.

BACKGROUND: The dynamic respiratory abnormalities in dogs with pectus excavatum are incompletely characterized. HYPOTHESIS/OBJECTIVES: To characterize fluoroscopic findings in dogs with pectus excavatum and evaluate their associations with clinical severity. ANIMALS: Fifty-three client-owned dogs with pectus excavatum. METHODS: Cross-sectional study. Dogs were classified into low-severity or high-severity groups based on respiratory signs and treatment. Fluoroscopic examinations were evaluated for pectus excavatum-intrinsic findings and concurrent respiratory abnormalities. Associations with clinical severity were assessed using univariable and multivariable analyses. RESULTS: Multiple fluoroscopic findings of pectus excavatum were characterized. Paradoxical sternal movement was independently associated with clinical severity (odds ratio [OR] 3.71, 95% CI, 1.03-13.4; P = .045). Thoracic height reduction ratio was significantly higher in the high-severity group (0.140 [IQR, 0.100-0.228]) compared with the low-severity group (0.097 [IQR, 0.064-0.133]; P = .04). Mainstem bronchial collapse was present in all dogs (53/53, 100%) and cervical lung lobe herniation in 50/53 (94%; 95% CI, 84%-99%). Most other fluoroscopic variables showed no significant associations with clinical severity. CONCLUSIONS AND CLINICAL IMPORTANCE: Paradoxical sternal movement, particularly with greater thoracic height reduction, may serve as a supportive indicator of clinical severity. The high prevalence of bronchial collapse and cervical lung lobe herniation suggests an association between pectus excavatum and these airway abnormalities in dogs.