Iowa State University Veterinarian Records, RS 22/6/0/9, University Archives, Special Collections Department, Iowa State University, http://www.add.lib.iastate.edu/spcl/arch/rgrp/22-6-0-9.html
Epidural analgesia is the injection of an anesthetic agent outside the dura mater producing a reversible motor and sensory paralysis of the spinal nerves. This is contrast to spinal analgesia, in which the local anesthetic is injected into the subarachnoid space.
Halley, Lynn E. and Riedesel, Dean H.
"Epidural Analgesia in the Dog,"
Iowa State University Veterinarian: Vol. 45
, Article 9.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol45/iss1/9