How to Place a Sacrococcygeal Epidural

April 2025
By Amanda M. Shelby, RVT, VTS (Anesthesia & Analgesia), VETgirl’s Senior CE Specialist and Dr. Amy Kaplan-Zattler, DACVECC, MRCVS, VETgirl CE Program Manager

In this VETgirl online veterinary continuing education blog, we demonstrate how to perform a sacrococcygeal (SC) epidural (aka – “SC block”, “caudal block”, “coccygeal block”) in a cat. The SC epidural can provide regional analgesia for procedures involving the tail, penis, or vulva.

In sternal recumbency, an approximately 4 x 4 cm square just proximal to the base of the tail is clipped and aseptically prepared (see Figure 1).

Figure 1. Sacrococcygeal location shaved for a SC epidural.

Wearing sterile gloves, the sacrococcygeal space is appreciated via digital palpation as shown below in Figure 2. With the help of an assistant or using a sterile drape wrapped around the tail, the tail is flexed and lowered in a hinge fashion to create a palpable dimple at the base of the tail.

Figure 2. Palpation of the sacrococcygeal junction. Photo courtesy of Amy Kaplan-Zattler

A 25 gauge, 1-in. needle is inserted into this space on midline (see Figure 3). A gentle “pop” may be appreciated when the ligamentum flavum has been penetrated. If, instead, bone is encountered at a superficial depth, walk the needle cranially or caudally until it sinks into the intervertebral space. If the needle is advanced too deeply and bone is met, this may indicate that the needle advanced to the floor of the vertebral canal. Simply remove the needle and try again.

Figure 3. Needle insertion into sacrococcygeal space. Photo courtesy of Amy Kaplan-Zattler

Once you feel the needle is in position, aspirate back to make sure you don’t get any blood back into your needle or syringe – aspiration of blood would necessitate removal of the needle and then reattempt with a new needle. Once in position, administer your anesthetic (commonly 0.1-0.2 mL/kg of 2% lidocaine or 0.22 mg/kg of 0.5% bupivacaine; recommended to used preservative-free formulations if available) up to a maximum volume of 0.2 mL/kg (see Figure 4). The average maximum volume for a cat is generally around 0.5 mL total volume.^{1, 2} There should be little resistance encountered during administration of the anesthetic.

Figure 4. Injecting the epidural solution. Photo courtesy of Amy Kaplan-Zattler

An effective SC block should result in a relaxed tail and perianal area. Depending on the drug administered, onset of effect should occur within 5 minutes for lidocaine and 8-10 minutes for bupivacaine, and with a duration of 1-2 hours (lidocaine) or 2-4 hours (bupivacaine).

If your patient will require prolonged pain relief, be sure to administer opioids before the epidural has worn off to continue supporting your patient’s comfort!

Watch our VETgirl continuing education video on the SC block in cats HERE.

Don’t have time to watch the video? You can listen to the Podcast instead!

References:
1. O’Hearn AK, Wright BD. Coccygeal epidural with local anesthetic for catheterization and pain management in the treatment of feline urethral obstruction. J Vet Emerg Crit Care 2011;21(1):50-2.
2. Pratt CL, Balakrishnan A, McGowan E, Drobatz KJ, Reineke EL. A prospective randomized, double-blinded clinical study evaluating the efficacy and safety of bupivacaine versus morphine-bupivacaine in caudal epidurals in cats with urethral obstruction. J Vet Emerg Crit Care 2020;30(2):170-178.