The purpose of this study was to assess antinociception and correlation of antinociception and hypothermic effects after intravenous opioids in dogs. Nine healthy male Beagles were enrolled in the study. They were acclimated to a thermal nociceptive device, then received three IV treatments (saline, butorphanol 0.4 mg/kg and methadone 0.5 mg/kg) in a randomized complete block design. Rectal temperature and thermal withdrawals were assessed prior to and 0.5–6 h after drug administration. One dog was excluded due to lack of withdrawal to thermal stimuli. Rectal temperatures were not significantly different between treatments at time 0, but significantly decreased from 0.5 to 5 h for both opioids compared to saline. Withdrawals were significantly decreased, compared to saline, from 0.5 to 4 h for butorphanol and 0.5–5 h for methadone. A significant (p = .0005) and moderate (R² = .43) correlation between antinociception and hypothermia occurred. Based on these data, intravenous butorphanol (0.4 mg/kg) and methadone (0.5 mg/kg) provided 4 and 5 h of antinociception, respectively. Opioid hypothermia can serve as an easy, noninvasive and humane manner for preclinical assessment of opioid antinociception in dogs prior to evaluation in clinical trials. This is a major refinement in animal welfare for assessing novel opioids, opioid doses and dose intervals in dogs.

中文翻译：

---

狗的阿片类镇痛作用与体温过低的相关性——动物福利的改进

本研究的目的是评估狗静脉注射阿片类药物后的抗伤害作用以及抗伤害作用与低温效果的相关性。九只健康的雄性比格犬参加了这项研究。他们适应了热伤害装置，然后在随机完整区组设计中接受三种静脉注射治疗（盐水、​​布托啡诺 0.4 毫克/公斤和美沙酮 0.5 毫克/公斤）。在给药前和给药后 0.5-6 小时评估直肠温度和热戒断反应。一只狗由于缺乏对热刺激的退缩而被排除在外。与生理盐水相比，两种阿片类药物在 0 时间处理之间的直肠温度没有显着差异，但从 0.5 小时到 5 小时显着下降。与生理盐水相比，戒断时间显着减少，布托啡诺为 0.5 至 4 小时，美沙酮为 0.5-5 小时。 镇痛与体温过低之间存在显着 ( p  = .0005) 和中等 ( R ^{2 = .43) 相关性。}根据这些数据，静脉注射布托啡诺 (0.4 mg/kg) 和美沙酮 (0.5 mg/kg) 分别提供 4 小时和 5 小时的镇痛作用。阿片类药物低温可以作为一种简单、无创和人道的方式，在临床试验评估之前对狗的阿片类药物镇痛作用进行临床前评估。这是动物福利方面的一项重大改进，用于评估狗的新型阿片类药物、阿片类药物剂量和剂量间隔。