Locoregional analgesia techniques

Angela Briganti DVM, PhD

The control of pain is a crucial point for the management of emergency and critical care patients. A multimodal approach to pain management and the use of locoregional analgesia (LRA) techniques are recommended in order to reduce side effects and the time of hospitalization.

Locoregional anesthesia by the injection of local anesthetics (LA) (table 98.1) stops afferent nociceptive signals by reversibly blocking sodium channels of the nerve fibers. 

Cats are uniquely sensitive to LA; for this reason the maximum dosage should be decided based on the clinical status of the animal. Concentration of LA has an impact on duration and efficacy of the block; higher concentrations lead to more solid and longer blocks.2

The volume of LA is important to ensure the nerve is completely surrounded by the LA solution. The volume needed depends on the technique employed: a blind technique needs a larger volume whilst ultrasound-guided techniques generally require smaller volumes. When performing LRA, one should first decide the kind of LA to use and calculate the maximum safe dosage; then one must decide the concentration and volume based on the selected technique (fig. 98.1).

Neuraxial techniques

Spinal anesthesia

With this technique the analgesic solution is injected in the subarachnoid space inside the cerebrospinal fluid (CSF). This technique allows selective blockade of some portion of the spinal cord, depending on the baricity of the injected solution in comparison to that of the CSF. Hypobaric solutions float over the CSF while hyperbaric solutions sink. Spinal injection can be done at L5-L6, L6-L7, or L7-S1. The technique is performed aseptically in sternal or lateral recumbency with a Quincke spinal needle. The use of a specific needle is important in order not to lacerate the dura mater. Flow of CSF from the needle hub confirms proper positioning of the tip of the needle. Bupivacaine 0.5% is generally used for this technique at a dosage 0.3-1.6 mg/kg and can be combined with preservative-free morphine.3 The mean duration of analgesia with this technique is 2-4 hours.

Epidural anesthesia

With this technique the analgesic solution is injected in the epidural space just under the yellow ligament. The solution desensitizes the metamers of spinal cord it reaches. The volume of solution injected is directly related to the extent of spinal cord blockade. 

Epidural injection can be done at the lumbosacral or sacrococcygeal spaces. The potential for dural puncture is meaningful given the small diameter of the vertebral canal and since the dural sac can extend to S1.

The sacrococcygeal approach is generally preferred in cats and has been proven to be safe and effective for the analgesic management of urethral obstruction.4,5 

The procedure is done aseptically with the cat in sternal recumbency. Tuohy needles are recommended as they allow recognition of passage through the interacuate ligament. Additionally, Tuohy needles have stylets to avoid transportation of superficial impurities into the epidural space.

The use of the nerve-stimulator set at 0.7 mA can help in identifying the correct position of the tip of the needle (video 98.1).6

The use of ultrasonography7 and color Doppler8 can be helpful in verifying the proper injection into the epidural space (video 98.1).

Bupivacaine 0.3-0.5% or ropivacaine 0.3-0.5% are the LA used for this technique (0.2-0.4 mL/kg) and can be combined with preservative-free morphine. The mean duration of analgesia with this technique is 6-10 hours.

Peripheral techniques

Peripheral techniques are categorized as infiltrative, truncal, interfascial, and intracavitary based on where the LA solution is injected. The technique can be performed blindly, with a nerve stimulator, or via ultrasound guidance. The use of the ultrasonography allows performance of these techniques with only mild sedation9 or in awake patients.

Topic anesthesia

Use of anesthetic creams on the skin, as well as splashing a LA solution over mucus membranes or opened cleaned wounds, can be options to reduce pain for some procedures (e.g., phlebotomy, skin suture, bandaging). Anesthetic creams generally have long onset (20-30 minutes), and splashing of anesthetic solutions requires high volumes.

Infiltrative anesthesia

Infiltrative anesthesia can be very useful for desensitization of small area of superficial tissue, of surgical wounds,10 and for extremities. In the latter case a ring block is a very effective and easy procedure that does not induce motor blockade (fig. 98.2).

Truncal anesthesia

Truncal anesthesia desensitizes large areas innervated by the blocked nerve. Sciatic blockade produces analgesia of the stifle (partial) and leg distal to the knee (complete). The sciatic nerve is readily identifiable via ultrasonography as two round hypoechoic structures in the middle of the quadriceps muscles in the lateral aspect of the leg (fig. 98.3). Blockade of the radial, ulnar, median and musculocutaneous (RUMM) nerves is used to desensitize the entire thoracic limb distal to the humerus head. This block is performed with ultrasound-guidance and blocks all four nerves with a single injection (fig. 98.4).11

Interfascial anesthesia

Increased use of ultrasonography has led to the development of techniques that involve injecting LA between two fascial planes where several nerves can be blocked concurrently. The transversus abdominis plane block is performed by injecting LA solution between the transversus abdominis and internal abdominal oblique muscles and leads to the desensitization of the abdominal wall (fig. 98.5).12 This block appears to be effective for managing pain due to pancreatitis.13

Intracavitary blocks

Intracavitary blocks can be performed by instilling LA solution into the pleural or peritoneal cavities for the management of visceral pain. The LA can be administered at the end of the surgery before closing the cavity or through specific infusion/drainage catheters.14


1. Tan M, Law LS, Gan TJ. Optimizing pain management to facilitate Enhanced Recovery After Surgery pathways. Can J Anaesth 62:203-218, 2015.

2. Portela DA, Otero PE, Tarragona L, Briganti A, Breghi G, Melanie P. Combined paravertebral plexus block and parasacral sciatic block in healthy dogs. Vet Anaesth Analg 37:531-541, 2010.

3. Sarotti D, Cattai A, Franci P. Combined spinal and general anaesthesia in 58 cats undergoing various surgical procedures: description of technique and retrospective perioperative evaluation. Feline Med Surg 21:1127-1133, 2019.

4. 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 (San Antonio) 21:50-52, 2011.

5. 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 (San Antonio) 30:170-178, 2020.

6. Otero PE, Verdier N, Zaccagnini AS, Fuensalida SE, Tarragona L, Portela DA. The use of a nerve stimulation test to confirm sacrococcygeal epidural needle placement in cats. Vet Anaesth Analg 42:115-118, 2015.

7. Credie L, Luna S. The use of ultrasound to evaluate sacrococcygeal epidural injections in cats. Vet J 59:143-146, 2018.

8. Castro D, Portela DA, Otero PE. Positive color flow Doppler test used to confirm sacrococcygeal epidural injection in a dog. Vet Anaesth Analg 47:280-281, 2020.

9. Campoy L, Martin-Flores M, Ludders JW, Gleed R. Procedural sedation combined with locoregional anesthesia for orthopedic surgery of the pelvic limb in 10 dogs: case series. Vet Anaesth Analg 39:436-440, 2012.

10. Vicente D, Bergström A. Evaluation of intraoperative analgesia provided by incisional lidocaine and bupivacaine in cats undergoing ovariohysterectomy. Med Surg 20:922-927, 2018.

11. Otero PE, Fuensalida SE, Sánchez F, Verdier N, Tarragona L, Briganti A, Portela DA. Development of a lateral ultrasound-guided approach for the proximal radial, ulnar, median and musculocutaneous (RUMM) nerve block in cats. Vet Anaesth Analg 47:686-693, 2020.

12. Skouropoulou D, Lacitignola L, Centonze P, Simone A, Crovace AM, Staffieri F. Perioperative analgesic effects of an ultrasound-guided transversus abdominis plane block with a mixture of bupivacaine and lidocaine in cats undergoing ovariectomy. Vet Anaesth Analg 45:374-383, 2018.

13. Freitag FA, Bozak VL, do CArmo MP, Froes TR, Duque JC. Continuous transversus abdominis plane block for analgesia in three dogs with abdominal pain. Vet Anaesth Analg 45:581-583, 2018.

14. Steagall PVM, Benito J, Monteiro B, Lascelles D, Kronen PW, Murrel JC, Roberston S, Wright B, Yamashita K. Intraperitoneal and incisional analgesia in small animals: simple, cost-effective techniques. J Small Anim Pract 61:19-23, 2020.


Locoregional analgesia techniques

No data for this chapter
video cover

Video 98.1 Execution of a nerve-stimulated sacrococcygeal epidural injection

This website uses cookies to ensure it functions correctly. By clicking ‘Accept’ you will allow the use of these cookies.