Sheep: a model for testing spinal and epidural anesthetic agents.

The sheep was utilized as a model to study local anesthetic agents used for subarachnoid and epidural anesthesia in human beings. Employing injection and evaluation technics similar to those used in human anesthesiology, the onset of anesthesia, development of maximum sensory anesthesia, regression of sensory anesthesia, and complete return of sensation and motor function were measured. Subarachnoid injection with 0.25% tetracaine and epidural injection with 0.25% bupivacaine produced regional anesthesia similar to that observed in humans.