Evaluation of analgesic and physiologic effects of epidural morphine administered at a thoracic or lumbar level in dogs undergoing thoracotomy.

Objective: To evaluate the analgesic and physiological effects of epidural morphine administered at the sixth and seventh lumbar or the fifth and sixth thoracic vertebrae in dogs undergoing thoracotomy.

Study Design: Prospective, randomized, blinded trial.

Animals: Fourteen mixed-breed dogs, weighing 8.