Measurement example of RLAD. Radiographic Left Atrial Dimension (RLAD) measurement in the same right lateral thoracic radiograph is seen in Figure 1. The long axis (white dotted line) was applied as described for the VHS measurement (Figure 1). The short axis (white dotted line) was drawn from the dorsal intersection of the caudal vena cava and the cardiac silhouette to the long axis. The bisecting RLAD line was drawn from the intersection point to the dorsal margin of the left atrium (red line on cardiac silhouette). This line was transposed onto the vertebral column (red line on vertebral) as described in Figure 1. The RLAD was 1.8 vertebral units.