COMPARISON BETWEEN SPLASH BLOCK VERSUS INJECTION OF LIDOCAINE ON THE OVARIAN PEDICLE IN CANINE OVARIECTOMY

Ovariectomy is a surgery with medium level of pain and requires an effective analgesic technique. Multimodal analgesia, including drugs administered both systemically and locally, is considered the most effective approach to providing pain relief and has been widely accepted in medicine veterinary medicine to control intraoperative pain (Acquafredda et al., 2021). Splash block is an analgesic technique already described by several authors in domestic animals, which consists of an irrigation of lidocaine in the ovarian pedicle to improve local analgesia during ovariectomy (Cicirelli et al., 2022). Furthermore, Grubb and Loprise (2020) describe direct infiltration of the ovarian pedicle with lidocaine. To our knowledge, the use of lidocaine infiltrated on the canine pedicle during ovariectomy has not yet been evaluated, or compared with other analgesic techniques. Although it is to be expected that additional local anaesthesia confer better analgesia, the aim of this study was to compare the analgesic efficacy of splash block versus the infiltration of lidocaine on the ovarian pedicle in bitches ovariectomy. Forty bitches of various breeds presented for ovariectomy were involved to this study after obtaining informed owner consent. After general examinations, all the dogs had a thoracic radiograph, abdominal ultrasound scan, and routine blood tests. Thus, the bitches were allocated to the very low aesthetic risk class (ASA 1) and randomly assigned in two groups (n=20) to receive topical irrigation (splash block) of 2% lidocaine (C group) on both ovarian pedicle (2 mg/kg each), or an equal volume of lidocaine infiltrated in the same sites (R group). This study was approved by the Ethics Committee for animal testing–CESA of the Department of Veterinary Medicine of the University of Bari Aldo Moro. The same surgical team performed all ovariectomy, in full compliance with the leges artis. In C group, prior to manipulation of the ovarian pedicles, 2% lidocaine was dripped on the ovarian pedicle (2 mg/kg each) using a catheter urinary (splash block). In R group, 2% lidocaine was infiltrated on the ovarian pedicle (2 mg/kg each) using a 2.5 mL syringe (23-G). Following lidocaine application, surgical manipulation was stopped for 90 seconds. Before the first incision, the hemodynamic parameters of all animals (preincisional values of heart, respiratory and blood non invasive pressure values) were recorded to evaluate pain responses to the surgical stimulus. These parameters were registered at six phases of the study: grasping of the ovary (time 1), dissection of the mesosalpinx (time 2), tightening of the first loop ligature (time 3), tightening of the second loop ligature (time 4), transection of the ovarian pedicle (time 5) and release of the ovary (time 6). Repeated-measures ANOVA showed no significant differences in heart rate, respiratory rate and blood pressure values between groups, neither during lidocaine infiltration on the ovarian pedicle. The results of the present study suggest that splash block may provide intraoperative analgesic effects equivalent to injection in the ovarian pedicle in dogs that have undergone ovariectomy. In fact, in both procedure, lidocaine is absorbed quickly from ovarian tissue blocking the ascending afferent input and interfering with ion channels of the nerves of ovaries, allowing a satisfactory intraoperative analgesia.