To characterize spinal cord effects of needle placement using lumbar puncture myelography technique, lumbar puncture was performed in 5 dogs and computed tomography images of the spinal column were acquired in the transverse plane at the level of the puncture site after contrast injection and both before and after needle removal. The spinal cords were punctured during needle placement and parenchymal contrast enhancement was present in 4 of 5 dogs. Although no dogs exhibited overt neurological abnormalities following computed tomographic imaging, hemorrhage, gliosis and axonal degeneration were confirmed microscopically in all subjects. These results suggest that spinal cord morbidity is induced when lumbar myelography is performed using currently accepted technique.