Ultrasound examination of the chest may identify fluid in the pleural cavity, found in horses with pleuropneumonia. This serious disease, known as "Shipping fever", is most commonly seen in horses that have travelled long distances. Ultrasound is the best way of identifying the presence and amount of fluid and to monitor treatment.

Ultrasound is also used to detect more subtle changes, such as thickening of the lining of the lungs or an irregular surface or movement of the lungs in horses with other respiratory problems.

Right: lung abscess in a racehorse