Azygos continuation of the caudal vena cava with segmental aneurysm, lung lobe torsion and pulmonary thromboembolism in a dog

Abstract

This case highlights the management and diagnostic evaluation of a dog with two individually rare conditions (lung lobe torsion and vena cava aneurysm) that ultimately resulted in fatal pulmonary thromboembolism.

Keywords: Blood clot; congenital; embolism; vascular anomaly.

Figure 1

Ventrodorsal and left lateral thoracic radiographs, illustrating lung lobe torsion. Note the abnormal position of the right middle lung lobe along with a vesicular gas pattern and inability to visualize the right middle lobar bronchus. These findings are typical for lung lobe torsion.

Figure 2

(A) Gross photograph of the thoracoabdominal cavity with most viscera removed, illustrating continuation of the abdominal caudal vena cava (with aneurysm) through the diaphragm as the azygos vein. The thoracic portion of the caudal vena cava, which terminated at the level of the liver, is not pictured as it was removed with the heart. (B) Photomicrograph of the lung depicting an occlusive pulmonary arterial thrombus (asterisk). A bronchus is located to the right of the thrombosed vessel, and hemorrhage is apparent in adjacent parenchyma to the left. Hematoxylin and eosin. Bar = 500 microns.