Radiographic Cardiac Measurements in Clinically Healthy Calves: Reference Values for VHS, VLAS, CTR, and CVC

This study aimed to establish reference values for thoracic radiographic cardiac measurements in clinically healthy calves aged 0-3 months and to evaluate their associations with age, sex, and breed. The assessed parameters included Vertebral Heart Score (VHS), Vertebral Left Atrial Size (VLAS), cardiothoracic ratio (CTR; recorded as CTO in the dataset), long axis (LA), short axis (SA), and caudal vena cava (CVC) diameter. A total of 100 clinically healthy calves (68 Simmental, 17 Brown Swiss/Montofon, 12 crossbred and 3 Holstein; 65 males and 35 females; 1-93 days old) presented to the Animal Hospital of the Faculty of Veterinary Medicine, Atatürk University, were included. Sedation was not used. Right lateral and dorsoventral thoracic radiographs were obtained, and measurements were performed using a DICOM/PACS system by two independent observers in a blinded manner, with three repeated measurements. VHS and VLAS were calculated in vertebral units. CTR (CTO) was defined as the ratio of maximal cardiac width to maximal internal thoracic width, while LA, SA, and CVC were recorded as linear measurements. Statistical analyses were conducted using MedCalc. Sex comparisons were performed with the Mann–Whitney U test, breed comparisons (excluding Holstein) with the Kruskal-Wallis test, and age effects with multivariable regression analysis. Absolute measurements (LA, SA, and CVC) increased significantly with age (p0.01), whereas VHS and CTR (CTO) remained stable (p0.05). Male calves showed higher LA, SA, and VLAS values than females (p0.05). No significant breed-related differences were detected. In conclusion, growth significantly affects absolute cardiac dimensions in young calves, while VHS and CTR/CTO remain stable, supporting their reliability as size-normalized radiographic indices during early life.