Spinal anesthesia with batrachotoxin in sheep and microscopic examination of spinal cords and roots.

Abstract Twelve sheep received total doses of 2 or 4 ug of BTX by spinal subarachnoid injection. These doses produced sensory analgesia that lasted from slightly less than an hour to more than 24 hours. In nine of the sheep, sensory analgesia was accompanied by motor block that lasted from less than an hour to more than 12 hours. All animals recovered completely from the blocks and exhibited no signs of sensory or motor impairment. However, microscopic examination of the spinal cords and roots of two of the sheep that had received total doses of 2 ug of BTX revealed morphological changes attributable to the toxin.