Evaluation of the Two-Point Ultrasound-Guided Transversus Abdominis Plane Block for Laparoscopic Canine Ovariectomy

SIMPLE SUMMARY: The transversus abdominis plane (TAP) block is an anesthetic technique that involves the injection of a local anesthetic to block the branches of the thoracolumbar spinal nerves innervating the abdominal wall and peritoneum. TAP has gained popularity in abdominal procedures, such as ovariectomy, but its use in veterinary laparoscopy remains poorly described. Among the different approaches described for TAP performance, the two-injection-point TAP results in a larger blocked area; however, clinical data on its efficacy are lacking. Our hypothesis is that a two-injection-point TAP could reduce the dose of intraoperative inhalational anesthetic and postoperative pain in dogs undergoing laparoscopic ovariectomy (LapOV). A total of 52 bitches were enrolled and divided into two groups: 26 were assigned to inhalational anesthesia, and 26 were assigned to inhalational anesthesia combined with TAP block. The end-tidal concentration of isoflurane and postoperative pain were assessed at different time points. The combination of the TAP block with inhalational anesthesia for the LapOV significantly reduced the requirements of isoflurane during the ovarian resection. Bitches that received TAP showed lower postoperative pain and required less analgesia intra- and postoperatively. The two-injection-point TAP block is an easy and effective anesthetic technique to provide postoperative analgesia to dogs undergoing LapOV. ABSTRACT: The transversus abdominis plane (TAP) block causes desensitization of the abdominal wall and peritoneum. Of all the approaches proposed to perform it, the two-injection-point TAP showed the best results in terms of the area reached by the anesthetic solution. However, to date, no clinical data exist. The aim of this study was to evaluate the intra- and postoperative analgesic efficacy of a two-injection-point TAP block in dogs undergoing laparoscopic ovariectomy. A total of 26 animals were assigned to receive general inhalation anesthesia (control group), and 26 dogs were assigned to general inhalation anesthesia combined with TAP block (TAP group). The ultrasound-guided TAP block was carried out with a subcostal and cranial-to-ilium injection per hemiabdomen. The end-tidal concentration of isoflurane (EtISO) was recorded at different moments during the surgery. Postoperative pain was assessed at different time points during the first 24 h after surgery. The control group required significantly higher EtISO concentration during the ovarian resection and showed higher postoperative pain scores than the TAP group. Fewer dogs in the TAP group required intra- or postoperative rescue analgesia. TAP block can be implemented to improve postoperative pain management after laparoscopy, reducing the dosage of the systemic drugs used and, hence, their possible side effects.