Computed tomography of the thorax in calves from birth to 105 days of age

The present study was undertaken to provide computed tomographic (CT) reference values for structures in the thorax of the calf. Six clinically healthy Holstein-Friesian calves were anaesthetized. Transverse pre- and postcontrast images with a reconstructed 1.5-mm slice thickness were obtained using a multislice-CT scanner at 6 different time points from birth to 105 days of age. Absolute and relative measurements of the trachea, heart, cranial and caudal vena cava, thoracic aorta, right and left principal bronchi, right and left caudal lobar bronchi and the accompanying branches of the right and left pulmonary artery and vein, thoracic lymph nodes and lung density were taken for every time point. All animals were euthanized after the last CT scan, and 4 calves were frozen to generate an atlas comparing gross anatomy with CT. During the study, 4 animals temporarily showed coughing and mucopurulent nasal discharge, and mild to moderate bronchopneumonia and pleuritis were diagnosed using CT. Animals recovered with treatment; however, mild to moderate CT changes remained throughout the study. Even in the 2 clinically normal animals, mild bronchopneumonia was diagnosed on CT.