DISCOGRAPHY AND EPIDUROGRAPHY FOR EVALUATION OF THE LUMBOSACRAL JUNCTION IN DOGS WITH CAUDA-EQUINA SYNDROME

Cauda equina syndrome in the dog is a common neurologic disorder caused by compression of the spinal cord, nerve roots and spinal nerves caudal to the fifth lumbar vertebra. This paper describes the clinical signs, radiographic findings of discography and/or epidurography, and comparison with surgery or necropsy of 21 dogs with cauda equina syndrome. Discograms were performed by using a 20- or 22-gauge spinal needle introduced in a sagittal plane into the lumbosacral (LS) disc space under fluoroscopic guidance. Epidurograms were performed following discography by injecting contrast medium after repositioning the tip of the needle into the ventral epidural space at the level of the LS junction. Direct examination of the LS junction was performed in all dogs by surgical exploration and/or necropsy. On survey radiographs, the most common findings were spondylosis, malalignment of the sacrum to the last lumbar vertebra, collapse of the LS disc space, stenosis of the vertebral canal at the LS junction, and transitional vertebral segments. Discography was considered of diagnostic quality in 19/21 (90%) of the dogs, showing disc protrusion in 14/21 (67%). Epidurography was of diagnostic quality in 18/18 (100%) dogs, showing abnormal findings in 14/18 (78%). No adverse reaction was noted to the radiographic procedure when dogs were allowed to recover from anesthesia before surgery. Based on macroscopic findings, combination of survey radiographs and discoepidurography was correctly positive in 16/18 dogs (89%). It is concluded that discography associated with epidurography is a valuable procedure for evaluation of the LS junction in the dog. A combination of both procedures reduces the possibility of technical artifacts by outlining both sides of the compressive lesion, i.e., the disc and the epidural space.