Lumbosacral spinal isolation in cat: surgical preparation and health maintenance

This paper describes a preparation in which the skeletal neuromuscular system of the hind limb of the adult cat is rendered permanently quiet with respect to electrical and contractile activity. The surgical method, regime for maintaining the health of the cats, and the condition of the cats are reported in detail. The characteristics of the isolated neuromuscular system are briefly summarized. The lumbosacral spinal cord carrying the innervation to the lower hind limb was surgically isolated from excitatory inputs from both dorsal root afferent fibers and upper motoneurons. This was accomplished by a bilateral dorsal rhizectomy between two transections of the cord, just rostral to the L5 segment and approximately at the S3 segment. The laminectomy was restricted to retain laminar structures sufficient to protect the cord from mechanical stimulation. During the rostral transection, the ventral artery was spared, preserving the blood supply to the ventral region of isolated cord. Daily maintenance and surveillance procedures were extremely important, but simple and brief. With strict adherence to procedures for both surgery and care, the cats remained healthy except for bladder infections, and their hind legs were in chronic flaccid paralysis.