Vertebral Scale System to Measure Heart Size on Thoracic Radiographs of Labrador Retriever Dogs

摘要

Radiological evaluation of the small animal thorax is one of the most important and frequently performed tests for the diagnosis of cardiac abnormalities. A guideline of 2.5 to 3.5 intercostal spaces for dogs was introduced in 1968 and is still used in veterinary medicine (Kealy, 1985). Limitations of this method included variations of the heart size and shape, conformation of the thorax, phase of respiration, superimposition of ribs, and imprecise measurement points. Buchanan and Bucheler (1995) described a method for measuring the canine cardiac silhouette that involved measuring its long and short axes in a lateral radiograph and comparing the sum of these measurements to the mid-thoracic vertebral bodies, to produce a unit-less index called Vertebral Heart Score (VHS). According to them, most normal dogs had a VHS of 8.7-10.7 vertebrae. However, recent studies at the Royal Veterinary College had shown that there are differences between breeds that must be taken into account when interpreting VHS.