"Shoulder lameness presents a diagnostic challenge to the practitioner," said Mary Beth Whitcomb, DVM, lecturer in surgical and radiological sciences at the University of California, Davis, in her presentation: "How to Perform a Complete Ultrasound Exam of the Equine Shoulder" during the 2003 American Association of Equine Practitioners convention. "Radiographs of this area have limited visibility, nuclear scintigraphy is expensive, and ultrasound is inexpensive and available to most practitioners.

"Examining the shoulder is indicated when there is swelling or trauma to the area and for forelimb lameness that's refractory (continues to be present) after a lower limb blocks," she recommended. "The shoulder is also a relatively common location for draining tracts. Ultrasound can be used to follow tracts into deeper tissues to identify foreign material, sequestered bone, or abscesses. It is important to remember that there may be multiple tracts and/or foreign bodies. Ultrasound can also be used to identify communication of these draining tracts with the synovial structures of the shoulder joint."

She said that a shoulder ultrasound examination should include evaluation of the following structures: Biceps tendon, bicipital bursa, humeral tubercles, scapula, tendons of attachment of the supraspinatus muscle and infraspinatus muscle and infraspinatus bursa.

Whitcomb noted that a practitioner gets the best images with the coat clipped using #40 blades, washed, and covered with ultrasound coupling gel. Alcohol can be used to improve contact in horses which can't be clipped. She noted that practitioners should use the highest frequency transducer available (preferably 7-10MHz), scanning at a depth of 4-6 cm. She described shoulder anatomy as seen on ultrasound in great detail for attendees