Imaging diagnosis: azygous continuation of the caudal vena cava with and without portocaval shunting.

The CT angiographic features of azygous continuation of an interrupted caudal vena cava in dogs with and without portocaval shunting are described. Azygous continuation of a discontinuous caudal vena cava is usually an incidental finding, not associated with portosystemic shunting. Identification of an associated portosystemic shunt will determine the need for surgical intervention. CT angiography provides a means for making this distinction and details the course and size of the anomalous vessels. Focal widening of the caudal vena cava on a VD thoracic radiograph should raise suspicion for azygous vein distension.