Right lateral radiograph illustrating an example of a vertebral heart scale calculation in a Brittany Spaniel suffering from a myxomatous mitral valve disease with a vertebral heart scale of 11.6 v (the image was acquired using a PICKER CONVIX 80–UNIVERSIX 120 device (Picker International, Uniontown, OH, USA); the kVp, mA, and time settings were not recorded). Two lines are drawn on the heart to measure its long and short axes. They are then transposed onto the spine and recorded as the number of vertebrae beginning with the cranial edge of T4. These values are estimated to one decimal place and added to obtain the vertebral heart size.