Thoracic radiographic anatomy in sheep

The objective of this study was to describe the normal radiographic anatomy of the thorax in sheep and to provide reference ranges for clinical use. Radiography of the thorax was performed in six East African blackheaded sheep. Right lateral (RL), left lateral (LL), dorsoventral (DV) and ventrodorsal (VD) radiographic views of the thorax were obtained under general anaesthesia at the end of inspiration. The number of thoracic vertebrae ranged from 12(1/6) to 13(5/6). The sternum was concave upward with the manubrium sterni almost vertically positioned. It consisted of manubrium sterni, xiphoid process and four (4/6) or five (2/6) sternebrae. There was no significant difference (P = 0.77) observed in the mean vertebral heart score (VHS) obtained on the LL (10.28 ± 0.37) and RL (10.23 ± 0.43) views. The mean ratio of the caudal vena cava (CVC) diameter to the height of the fourth thoracic vertebral body and aorta diameter was 1.19 ± 0.08 and 0.85 ± 0.08, respectively. The mean VHS on the VD view (8.62 ± 0.40) was significantly (P = 0.02) larger compared to that of the DV view (8.03 ± 0.25). The mean ratio of the trachea diameter to thoracic inlet distance was 0.14 ± 0.03. The right pulmonary cupula pleura was more radiolucent, wide and extended further cranially than the left pulmonary cupula pleura. Knowledge of the normal thoracic radiographic anatomy of individual species is important for accurate interpretation of thoracic radiographs.Keywords: sheep, thorax, radiography, anatom