Effects of Topical Administration of Bupivacaine HCl to the Ovarian Pedicle on Postoperative Pain, Antioxidant Enzyme Activity and Inflammatory Cytokines in Dogs Undergoing Laparoscopic Ovariectomy.

BACKGROUND

Laparoscopic ovariectomy (LOE) is a common procedure for elective sterilization in dogs and is associated with less tissue trauma than open techniques. However, manipulation of the ovarian pedicle may still induce nociceptive stimulation and contribute to perioperative inflammatory responses and changes in antioxidant enzyme activity. Topical administration of local anaesthetic to the ovarian pedicle may improve perioperative analgesia in minimally invasive surgery.

OBJECTIVES

To evaluate the effects of topical administration of bupivacaine HCl to the ovarian pedicle on postoperative pain, serum antioxidant enzyme activity and systemic pro-inflammatory cytokines in dogs undergoing LOE.

METHODS

Twenty-four clinically healthy, American Society of Anaesthesiologists (ASA) Class I female dogs were enrolled in a prospective, randomized, controlled trial. The dogs were allocated to receive either a total dose of bupivacaine HCl at 2.2 mg/kg (BPLOVE, n = 12), divided between the two ovarian pedicles, or an equivalent volume of isotonic saline (LOVE, n = 12), applied using the same topical technique. Standardized anaesthesia and surgical protocols were implemented. Postoperative pain was assessed using the University of Melbourne Pain Scale (UMPS) at 0, 2 and 4 h after surgery. Serum samples collected preoperatively, intraoperatively, and at 0, 2 and 4 h postoperatively were analysed for superoxide dismutase (SOD), catalase (CAT), interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α). Data were analysed using repeated-measures ANOVA and non-parametric tests (p < 0.05).

RESULTS

All dogs completed the study without experiencing any major complications or requiring intraoperative rescue analgesia. UMPS scores were significantly lower in the BPLOVE group at all postoperative time points (p < 0.05). Significant group and time effects were observed in SOD and CAT activities, with higher antioxidant enzyme activity detected in bupivacaine-treated dogs (p < 0.05). Cytokine outcomes showed no consistent between-group differences; IL-6 was numerically lower in the BPLOVE group across time points, with a significant difference detected only at 4 h postoperatively.

CONCLUSIONS

Topical administration of bupivacaine HCl to the ovarian pedicle during LOE was associated with improved early postoperative analgesia and higher serum SOD and CAT activities, without consistent short-term changes in systemic pro-inflammatory cytokine concentrations. These findings support the potential value of ovarian pedicle bupivacaine administration as part of multimodal analgesia in canine laparoscopic surgery and indicate changes in antioxidant enzyme activity during the early perioperative period.