Frontiers in veterinary science
Analgesic effect of methadone constant rate infusion is not superior to fentanyl constant rate infusion in dogs after spinal surgery: a prospective, randomized, blinded, clinical trial
By Schütter AF, Kästner SBR, Prause B and 1 others.
Abstract
Objectives
This study aimed to compare the analgesic efficacy of methadone and fentanyl infusions at a 50:1 dose rate in dogs after spinal surgery.
Methods
In a prospective, randomized, blinded clinical trial, 42 dogs with intervertebral disk disease were evaluated at 1, 2, 4, 18, 24, 42, 48, 66, 72, 90, and 96 h after extubation. Based on the treatment groups, the dogs received a presurgical bolus of 0.25 mg/kg methadone or 5 μg/kg fentanyl, followed by an intraoperative and postoperative opioid infusion. In the methadone (M) treatment group, the dogs received 0.2 mg/kg/h methadone, which was reduced stepwise to 0.05 mg/kg/h. In the fentanyl (F) treatment group, the initial dose of 5 μg/kg/h was reduced stepwise to 1 μg/kg/h. Assessments at each time point included a simple sedation score, vital parameters, pain scoring using the Glasgow Composite Measure Pain Scale (CMPS-SF), and sensory testing with von Frey filaments. Multiple Mann-Whitney tests were used for the analysis of CMPS-SF scores and sedation scores. Vital parameters, between and within the groups, were analyzed using mixed-effects analysis and Dunnett's multiple comparison test. The need for rescue analgesia was assessed via survival analysis. The level of significance was set to α = 5%.
