Ultrasonography of the suspensory ligament branches in yearling and 2-year-old Thoroughbred sales horses: Prevalence, progression of findings and associations with racing performance.

Reference values specific to young Thoroughbreds have been established. Grade 1 fibrillar branch change should be regarded as an acceptable appearance in sales yearlings and 2-year-olds. Approximately one-third of grade 2 yearling branches progressed to a grade 3 lesion. Evidence of enlarged branch width and grade 2 hyperechoic foci at 2-year-old sales constitute a risk to racing performance.