Use of Caudal Quadratus Lumborum Block with Ropivacaine as Part of an Opioid-Free Analgesic Protocol in Dogs Undergoing Orchiectomy: A Randomized Trial

Pain control is challenging in both human and veterinary medicine. The advantages of loco-regional anesthesia are widely known. In the last decade in veterinary medicine, the study of loco-regional interfascial techniques has grown exponentially. The study aims to evaluate the sparing effect on opioid consumption of the Quadratus Lumborum block performed at the level of the sixth lumbar vertebra in dogs undergoing elective orchiectomy. The results show an effective reduction in intraoperative consumption of fentanyl in the experimental group receiving the Quadratus Lumborum block compared to the control group. No statistically significant difference was found in methadone consumption in the post-operative period. No complications have been reported when performing the Quadratus Lumborum block at the level of the sixth lumbar vertebra. The results of this study suggest that the loco-regional anesthesia technique has an opioid-sparing effect on the surgical procedure proposed. In veterinary medicine, the use of loco-regional anesthesia techniques is increasing. The Quadratus Lumborum block (QL) is an interfascial loco-regional technique that involves the release of local anesthetic (LA) between the Quadratus Lumborum and the Small Psoas (Pm) muscle. The study aims to evaluate the effect of the QL block on reducing the total amount of opioids in dogs undergoing pre-scrotal orchiectomy. A group of 36 dogs was enrolled in a randomized blinded study. The animals were divided into two groups: 18 in the experimental group (QL) and 18 in the control group (C). The QL group received 0.4 mL kg(-1) of ropivacaine 0.5% for each hemiabdomen (total amount of 3 mg kg(-1) of ropivacaine, 1.5 mg kg(-1) per side). The C group was brought into the operating room (OR) after receiving the same clipping as the QL group. In the intraoperative period, opioid consumption in the QL group was significantly lower than in the C group. No differences were found in the post-operative phase. No side effects were reported when performing the QL technique. The QL block performed at the level of L6 appears to be a valid approach to reducing opioid use in dogs undergoing orchidectomy with a pre-scrotal surgical approach.