Measurement example of VHS. Right lateral thoracic radiograph displaying the Vertebral Heart Size (VHS) measurement in a dog of the control group. The long axis was drawn from the ventral margin of the carina tracheae to the most distal margin of the cardiac apex, and perpendicular to the short axis was drawn at the level of the ventral intersection of the caudal vena cava and the cardiac silhouette (red lines on cardiac silhouette). These lines were repositioned onto the vertebral column (red lines on vertebral column) beginning at the cranial margin of the fourth thoracic vertebrae. The VHS was 10.5 vertebral units.