Post-operative nausea and vomiting (PONV) observed in a clinical study designed to assess the analgesic effects of intravenous and subcutaneous methadone in dogs.

Opioids are a key component of multimodal analgesia. Methadone is licensed in Europe for IV, IM and SC use in dogs despite there being no published studies assessing the analgesic efficacy of SC administration. Our intention was to compare the analgesic effect of IV or SC methadone. Fifteen dogs presenting for stifle surgery were administered 0.4 mg/kg methadone IV followed by a randomised 0.0.4 mg/kg methadone IV or SC dose 3 h later. All dogs received ultrasound-guided sciatic and saphenous nerve blocks with bupivacaine prior to surgery. This protocol resulted in opioid adverse effects (hypersalivation, vomiting and/or regurgitation) in 5/15 dogs (33%). Thus, in consultation with the ethical review committee, an otherwise identical protocol using a revised 0.2 mg/kg methadone dose was implemented. In the next three dogs studied, similar opioid adverse effects were found in all three dogs and the study was terminated. This paper highlights the potential for post operative nausea and vomiting (PONV), which may have been induced by methadone when used in combination with efficacious locoregional anaesthesia.

Intra-articular mepivacaine reduces interventional analgesia requirements during arthroscopic surgery in dogs.

OBJECTIVES: To document efficacy of intra-articular mepivacaine in dogs based on the hypothesis that this would blunt the haemodynamic response to a nociceptive stimulus (arthroscopic surgery), reducing interventional analgesia requirements. METHODS: A dose of mepivacaine 2% 0 · 1 ml/kg (2 mg/kg) was injected intra-articularly into one randomly assigned elbow joint before surgery in eight dogs undergoing bilateral elbow arthroscopy. Baseline haemodynamic measurements were recorded immediately before the start of each arthroscopic procedure and repeated at arthrocentesis, saline distension of the joint, incision, arthroscopic cannula and obturator insertion and placement of the second portal and haemodynamic variability calculated. If baseline parameters increased by more than 20% suggesting nociception, 1 µg/kg fentanyl was administered intravenously. RESULTS: Significantly less fentanyl was required during arthroscopy on the mepivacaine treated elbows compared to the non-treated elbows (P = 0 · 003) and the time to first fentanyl administration was significantly longer (P = 0 · 0001) in the mepivacaine treated elbows (21 · 2 ± 4 · 9 minutes) compared to the non-treated elbows (6 · 1 ± 2 · 3 minutes). Haemodynamic variability was significantly reduced in the mepivacaine group (heart rate P = 0 · 04, mean arterial pressure P = 0 · 003). CLINICAL SIGNIFICANCE: Intra-articular mepivacaine blunts the haemodynamic response to arthroscopic surgery in dogs and reduces interventional analgesia requirement.

Pharmacological options for intra-operative and early postoperative analgesia: an update.

The motto of the 2011 Global Year Against Acute Pain was 'Anticipate, Assess, Alleviate'. Recent advances in acute pain management include novel applications of widely used drugs, new techniques, as well as further development in our knowledge of pain scoring in veterinary patients. The concept of preventive analgesia is introduced here and serves to strengthen the widely accepted practice of pre-emptive, multimodal analgesia.

Intra-articular morphine, bupivacaine or no treatment for postoperative analgesia following unilateral elbow joint arthroscopy.

OBJECTIVES: To compare intra-articular morphine or bupivacaine against no treatment following unilateral elbow joint arthroscopy using force plate analysis and pain scoring. METHODS: Thirty-one dogs were randomly allocated to receive 0·1 mg/kg intra-articular morphine, 0·5 mg/kg bupivacaine or no treatment following elbow arthroscopy. Force plate analysis, pain scoring and kinematic evaluation were performed before anaesthesia, 4 and 24 hours after surgery. Peak vertical force index, symmetry index, rate of loading, rate of unloading, stance time and range of motion were obtained from gait analysis. Pain scoring was performed every 4 hours and interventional analgesia (0·3 mg/kg methadone) was administered if necessary. RESULTS: Of 29 dogs analysed, peak vertical force index (P<0·001), symmetry index (P=0·01) and rate of unloading (P=0·01) decreased significantly over time in each group; however, this was not affected by treatment. No significant differences were observed in stance time or rate of loading over time. Kinematic (range of motion) evaluation was not complete for all dogs. Pain scores increased significantly at both time points postoperatively in the no treatment group (P=0·007) and in morphine-treated dogs at 4 hours compared to baseline (P=0·03). For intra-articular bupivacaine significant increases in pain scores were not detected (P=0·28). CLINICAL SIGNIFICANCE: No benefit to intra-articular bupivacaine or morphine was detected using peak vertical force index from force plate analysis. Bupivacaine prevented increases in pain scores at both time points as did morphine at the 24-hour evaluation, compared to no treatment.