Vertebral scale system to measure heart size in growing puppies

Objective - To determine relative heart size in clinically normal puppies a nd assess whether relative heart size changes with growth. Design - Prospective radiographic study. Animals - 11 puppies without evidence of disease. Procedure - Standardized measurements of the long and short axes of the hea rt, midthoracic vertebrae, and other structures were made at 3, 6, 12, and 36 months of age, Measurements were recorded in millimeters and number of t horacic vertebral lengths spanned by each dimension, measured caudally from T4 on lateral radiographic views. The long and short axis measurements of the heart, expressed in vertebral lengths, were added to yield vertebral he art size. Results - Mean +/- SD vertebral heart sizes on lateral radiographic views a t 3, 6, 12, and 36 months of age were 10.0 +/- 0.5, 9.8 +/- 0.4, 9.9 +/- 0. 6, and 10.3 +/- 0.6 vertebrae, respectively. Significant differences were n ot detected. Conclusions and Clinical Relevance - Vertebral heart size measurements in p uppies are within the reference range for adult dogs (9.7 +/- 0.5 vertebrae ) and do not change significantly with growth to 3 years of age. Standards for determining cardiac enlargement are similar in puppies and adult dogs.