Thoracic Ultrasound

Ultrasonographic examination of the thorax can provide useful information regarding pathology of the pleural cavity, the pleural surfaces, as well as the superficial pulmonary parenchyma.

The normal anatomy
The thoracic cavity of the horse extends from approximately the 5th to the 16/17th intercostal spaces. The mediastinum separates the 2 pleural cavities. The pleural cavities are lined by the visceral (lung surface) and parietal (rib/intercostal surface) pleura. The mediastinum between the 2 pleural cavities is typically fenestrated (incomplete) in horses.

Indications for and limitations of pulmonary ultrasound
Pulmonary ultrasound can be used to investigate the aetiology of many respiratory disorders in horses and foals. Because the ultrasound beam will be reflected by air, it is most useful when there are pleural disorders or pulmonary pathology at the lung periphery. Pulmonary pathology that is deep to normally aerated lung will not be visualised via ultrasonography. As such, it is often useful to combine both pulmonary ultrasonography and thoracic radiographs to investigate suspected thoracic disorders. [...]