An epidural injection of an opioid and/or a local anesthetic is most commonly given under anesthesia, immediately prior to abdominal or pelvic limb surgery. Readers are referred to texts for information on specific drugs and dosages.
The site for epidural injection is the lumbosacral space in both dogs and cats. The patient is placed in sternal recumbency with the pelvic limbs positioned cranially. The lumbosacral space is palpated between the ilial wings and the dorsal spinous processes of L7 and S1. The injection site is clipped and aseptically prepared. A 20 or 22 gauge spinal needle in passed into the LS space and through the ligamentum flavum. The saline bubble test is used to confirm proper needle placement in the epidural space; the analgesic injection is made and the needle is removed.
Advantages of preoperative epidurals include reduction of the concentration of inhalant anesthetics, smooth recovery, and postoperative analgesia lasting 8-24 hours. Potential complications of the technique could include respiratory depression, temporary loss of motor function or urine retention, or pruritus.