Describe a basic ultrasound approach to evaluating the proximal suspensory ligament in the hind limb.

Describe a basic ultrasound approach to evaluating the proximal suspensory ligament in the hind limb.

• A. Place the transducer along the ventral aspect of the fetlock.
• B. Position the horse squarely, place the transducer along the lateral cannon bone at the proximal suspensory region, evaluate fiber pattern and swelling, and compare with the other limb.
• C. Use the transducer on the dorsal aspect of the cannon bone.
• D. Scan with the leg fully flexed in a tight flexion.

Answer: (B)

Evaluating the proximal suspensory ligament with ultrasound is most informative when the limb is stable and weight-bearing, and you image along the lateral cannon bone at the proximal suspensory region. This position aligns the ultrasound beam with the ligament fibers, giving a clear long-axis view of the fiber pattern. You can assess for irregularities in the fibers, increased thickening, or hypoechoic areas that suggest injury, as well as any swelling around the ligament. Comparing the scanned limb with the opposite limb helps distinguish true pathology from normal asymmetry.

Other scan locations or positions don’t visualize the PSL as effectively. Ventral scanning at the fetlock tends to image other structures and may miss PSL changes. Scanning the dorsal aspect questions the image of the ligament, focusing instead on extensor tendons, which isn’t ideal for PSL evaluation. Fully flexing the leg alters tension and geometry, making the ligament harder to assess accurately.