Right lateral thoracic radiographic image of a CKCS demonstrating the radiographic measurements of modified version of vertebral left atrial size (M‐VLAS) performed in this study (kVp 75, mAs 2.5). An initial line (solid line) was drawn from the center of the most ventral aspect of the carina to the intersection between the most caudal aspect of the left atrium and the dorsal border of the caudal vena cava (#). A second additional line (dotted line) was then drawn from the most distal border of the left atrium towards the first line, intersecting it perpendicularly. Two separate straight lines corresponding to the lengths of the first 2 lines were then drawn from the cranial edge of the T4 (*) and summed (2 vertebrae in this example)