Comparison of the effects of lidocaine versus lidocaine and xylazine for proximal paravertebral nerve blocks in adult dairy cattle

Paravertebral nerve blocks provide regional anesthesia to the abdominal flank by anesthetizing the 13th thoracic (T13) spinal nerve and first (L1) and second (L2) lumbar spinal nerves. The anesthesia provided to the associated abdominal muscles and peritoneum of the affected dermatomes make these useful for standing abdominal surgeries performed in adult cattle. While lidocaine is the typical local anesthetic used, the duration of ac­tion produced may be variable leading to the anesthetic effects wearing off before the end of longer surgeries. Xylazine, an al­pha-2 adrenoceptor agonist, has been reported to augment an­esthetic and analgesic effects when used with lidocaine in other blocks (Grubb et al., 2002; Shokry and Elkasapy, 2018). Xylazine is a relatively inexpensive drug and has a short withdrawal time, making it a good option for cattle. Increasing the duration of action of the block will not only provide longer coverage dur­ing prolonged surgeries, but also aid in post-operative pain con­trol. The objective was to compare the length of duration of the analgesic effects of proximal paravertebral nerve blocks using lidocaine alone compared with lidocaine and xylazine in adult dairy cattle. The hypothesis was that the duration of action of the lidocaine-xylazine group would be longer than the lidocaine only group.