Analgesic Effect of Butorphanol and Levomethadone in Detomidine Sedated Horses

Abstract

The analgesic potency of butorphanol 25 microg/kg bodyweight (BW) and levomethadone 100 microg/kg BW, administered together with detomidine 10 microg/kg BW, was measured in twelve Warmblood horses in a randomized, blinded cross-over study. Detomidine with saline 10 ml 0.9% was used as placebo. The nociceptive threshold was determined using a constant current and a pneumatic pressure model for somatic pair Detomidine alone and in combination with butorphanol or levomethadone caused a significant temporary increase (P < 0.05) of the nociceptive threshold with a maximum effect within 15 min and a return to baseline levels within 90 min. Butorphanol and levomethadone increased the nociceptive threshold and prolonged the duration of anti-nociception significantly from 15 to 75 min (P < 0.05) after drug administration compared with detomidine alone to both test methods. No significant difference between butorphanol and levomethadone was registered. It is concluded that the addition of butorphanol or levomethadone to detomidine increases the nociceptive threshold to somatic pain and prolongs the analgesic effect of detomidine in the horse.

Antinociceptive effects of methadone combined with detomidine or acepromazine in horses

“…The increased antinociception observed in the detomidine/methadone group was expected and most likely attributable to synergism between methadone and detomidine. Although in a previous study , the antinociceptive effect of detomidine alone was evident, in agreement with widely reported observations , methadone alone at the same dose as in our study barely increased the electrical threshold and did not change the thermal threshold. However, both electrical and thermal antinociception were greatly increased in that study when detomidine was combined with methadone.…”

Effect of butorphanol administration on cardiovascular parameters in isoflurane-anesthetized horses – a retrospective clinical evaluation

“…Horses in this study that received multiple doses of butorphanol received the doses approximately 70 minutes apart. This is approximately the duration of analgesia afforded by butorphanol (Muir & Robertson 1985; Schatzman et al. 2001).…”

Validation of mechanical, electrical and thermal nociceptive stimulation methods in horses

“…A number of mechanical nociceptive threshold testing methods have been reported, and a variety of probes have been employed in horses [18,32,33]. We tested 4 different probes in a preliminary study and selected the 1 mm probe for the present study because this resulted in the lowest and least variable thresholds [34].…”

“…Electrodes have been implanted in the tooth pulp [36], fixed to the coronary band [18,35] or to the digital palmar nerve [15,37]. Electrodes have been implanted in the tooth pulp [36], fixed to the coronary band [18,35] or to the digital palmar nerve [15,37].…”