Lumbosacral Junction Abnormalities in Horses

Abnormal findings of the lumbosacral junction causing back pain are often detected with ultrasonography and include 1) congenital abnormalities such as lumbosacral ankylosis (sacralization of L6) or intervertebral ankylosis between L5 and L6; 2) disc degenerative lesions, especially affecting the lumbosacral disc (lesions include fissuration or cavitation of the disc, dystrophic mineralization, and ventral herniation); 3) intervertebral malalignment (spondylolisthesis) of the lumbosacral joint or the joint between L5 and L6; and 4) intertransverse lumbosacral osteoarthrosis (periarticular osteophytes or remodeling at the joint margins).