Measurement example of LAWidth. The Left Atrial Width (LAWidth) measurement in the same right lateral thoracic radiograph is shown in Figure 1. The long axis was measured as described in Figure 1 (white dotted line). The short axis was drawn at a 90° angle to the long axis at the height of the dorsal intersection between the cardiac silhouette and the caudal vena cava (red line on cardiac silhouette). This line was repositioned onto the vertebral column (red line on vertebral) as described in Figure 1. The LAWidth was 1.6 vertebral units.