Ultrasonographic Diagnosis of Acute Extrusion of the Lateral Meniscus in a Competing Quarter Horse

A 4-year-old Quarter Horse gelding with a history of acute trauma was presented to our faculty. This report describes the inciting injury, documented in a video, and the ultrasonographic diagnosis of a traumatic extrusion of the right lateral meniscus with an accompanying extra-articular hematoma and distal collateral ligament lesion in a competing Quarter Horse. The ultrasonographic diagnosis of a lateral meniscal injury directly correlated with postmortem findings and this type of lateral meniscal injury has not been previously described in detail.