Intratesticular and incisional line infiltration with ropivacaine for castration in medetomidine–butorphanol–midazolam sedated dogs

Abstract

ObjectiveTo evaluate whether intratesticular and incisional ropivacaine infiltration produces sufficient intra- and postoperative analgesia for castrating dogs under sedation. Study designRandomized, blinded, controlled clinical study. AnimalsTwenty-three healthy dogs weighing 5.8–35.6 kg admitted for castration. MethodsDogs were sedated with medetomidine (0.01 mg kg−1), butorphanol (0.2 mg kg−1) and midazolam (0.2 mg kg−1) intramuscularly, and were randomly assigned to group R, 0.2–0.4 mL kg−1 of ropivacaine 0.5%, or group S, an equivalent volume of saline injected intratesticularly and along the incision line. If persistent motion was observed during surgery, sedation was considered to be insufficient and general anaesthesia was induced. Carprofen 2.2 mg kg−1 was administered postoperatively. Pain was evaluated in all dogs before sedation and postoperatively following atipamezole administration at 1, 2, 4, 8 and 24 hours using an interactive visual analogue scale (IVAS; 0–100), the Glasgow composite pain scale-short form (CMPS-SF; 0–24), and a mechanical algometer. Methadone 0.3 mg kg−1 was administered intravenously to dogs if IVAS >30 or CMPS-SF >4. ResultsThere was no significant difference between groups for the number of dogs administered general anaesthesia. The time from the beginning of surgery to induction of general anaesthesia was significantly shorter [median (range)] in group S [6 (3–25) minutes] than in group R [56 (36–76) minutes]. At 8 hours IVAS was significantly higher in group S (14 ± 10) than in group R (6 ± 4). Conclusions and clinical relevanceIntratesticular and incisional ropivacaine infiltration delayed the time to anaesthesia induction, and provided analgesia after castration performed under deep sedation in dogs. Intratesticular local anaesthesia can be an important part of the anaesthetic plan for castration.