A novel method for evaluating thoracic radiographs in dogs with pulmonary stenosis

Pulmonary stenosis (PS) is a common congenital heart disease in dogs, often associated with poststenotic dilation of the pulmonary trunk or main pulmonary artery (MPA). We hypothesized that vertebrae-based radiographic measurement of the MPA might identify dogs with PS and potentially assess its severity.

A retrospective cohort study of 29 dogs with PS, 30 normal dogs, and 30 dogs with myxomatous mitral valve disease was conducted. Vertebral main pulmonary artery size (VMPS) was measured using dorsoventral (vertebral main pulmonary artery size measured using the dorsoventral radiograph [VMPS-DV] type 1, type 2) and right lateral (vertebral main pulmonary artery size measured using the right lateral radiograph [VMPS-LATE]) thoracic radiographs. Group differences were analyzed using the Kruskal-Wallis test. Correlation between VMPS and maximal instantaneous pressure gradient (continuous wave Doppler) was assessed using Spearman's correlation. Diagnostic performance was evaluated using receiver-operator characteristic analysis with Youden's index.

Vertebral main pulmonary artery size measured using the dorsoventral radiograph type 1 and VMPS-LATE were significantly greater in the PS group than in the normal group (P<0.001) but not significantly different from the myxomatous mitral valve disease group. After excluding French bulldogs, these indices remained significantly elevated. A VMPS-DV type 1 > 1.06 and a VMPS-LATE >3.6 were identified as optimal cutoffs for distinguishing dogs with PS from normal. No significant correlations between VMPS and pressure gradient were identified.

small sample size limited statistical power. Due to the absence of echocardiographic data, a comparison of MPA size between radiographic and echocardiographic modalities was not possible.

Although VMPS did not reflect PS severity, a VMPS-DV type 1 > 1.06 and a VMPS-LATE >3.60 support the diagnosis of PS in dogs with compatible clinical findings.