Abstract

Pulmonary disease is a leading cause of morbidity and mortality in cetaceans, frequently affecting animals in the wild and under human care. The purpose of this study was to present the normal computed tomographic (CT) appearance of the thorax of the live bottlenose dolphin (Tursiops truncatus) and to describe the technical and logistical parameters involved in image acquisition. Six thoracic CT evaluations of four conscious adult dolphins were performed between April 2007 and May 2012. Following voluntary beaching from ocean pens, the animals were transported to a CT facility on protective foam pads in covered trucks. Under sedation (0.02–0.09 mg/kg midazolam IM), dolphins were secured in ventral recumbency with tucked pectoral flippers for data acquisition using a GE Lightspeed® RT 16 helical CT (80 cm gantry, 227 kg table limit). Equipment was protected with plastic sheeting and water judiciously misted onto the animals' skin. Non-contrast helical images were obtained opportunistically during an end-inspiratory breath hold using contiguous 1.25 mm slices, a pitch of 1.75, 140 kVp, and auto mA (300–715). Diagnostic, high quality images were obtained in all cases. Respiratory motion was largely insignificant due to the dolphins' normal apneustic respiratory pattern. Unique anatomical considerations included the presence of a right tracheal bronchus, absence of lung lobation, cervical extension of lung, dorsoventrally compressed heart, lack of conspicuity of thoracic lymph nodes, and presence of retia mirabilia. Thoracic CT in live dolphins is both feasible and clinically valuable. A series of normal reference images is presented and compared to isolated examples of thoracic disease.

Acknowledgements

The author would like to thank Veronica Cendejas for her technical expertise in creating the line drawings used in this presentation, the U.S. Navy Marine Mammal Program, and the Office of Naval Research.

* Presenting author