Ultrasonography was used to delineate the sonographic anatomy of the equine crus, emphasizing the peroneus tertius muscle and the Achilles tendon. The cross‐sectional gross anatomy was studied in 6 cadaveric limbs. Using a 5.5 MHz mechanical sector scanner the examined Achilles tendon and per‐ oneus tertius muscle were easily identified as hyperechoic structures in 10 limbs of normal live horses. In 4 lame horses diagnostic ultrasound aided the diagnosis of peroneus tertius rupture, haematoma of the lateral digital extensor muscle and the presence or absence of Achilles tendon injury associated with intertendinous calcaneal bursi