Sedation and mechanical antinociception after intravenous administration of detomidine in donkeys: a dosage–effect study

Abstract

There is limited, useful, scientific information on detomidine in donkeys. This study compared the effects of intravenous saline, detomidine (10, 13.5, 17 and 20 μg/kg) and acepromazine (50 μg/kg) in donkeys by computing areas under the curve for 0-30, 30-60 and 60-120 minutes (AUC0-30, AUC30-60 and AUC60-120) for sedation scores, head heights and mechanical nociceptive thresholds (MNTs). For sedation scores, all detomidine treatments, except 10 μg/kg, increased AUC0-30 values compared with saline, and AUC0-30 values were larger for 17 μg/kg detomidine than for acepromazine. All head height AUC values were lower for detomidine than for saline (except AUC60-120 for 10 μg/kg detomidine) and acepromazine (except AUC0-30 for 10 and 20 μg/kg detomidine, and AUC60-120 for 10 μg/kg detomidine). For MNTs, all detomidine treatments increased AUC0-30 and AUC30-60 values compared with saline and acepromazine; AUC30-60 values were smaller for 10 μg/kg than for 17 and 20 μg/kg detomidine. MNT AUC60-120 values were larger for 20 μg/kg detomidine than for saline, 10 μg/kg detomidine and acepromazine. Detomidine induced sedation and antinociception, but only antinociception was dosage dependent. Selection of detomidine dosage for donkeys may depend on the required duration of sedation and/or degree of analgesia.

Sedative and cardiorespiratory effects of low doses of xylazine with and without acepromazine in Nordestino donkeys

“…Donkeys receiving the higher dose of xylazine showed HHAG values below 50% of the baseline values, whereas this did not occur when using the low dose of xylazine in combination with acepromazine. Intravenous acepromazine alone (0.05 mg/kg bwt) did not produce sedative effects (no reductions in HHAG), confirming the results of Lizarraga et al [12]; higher doses (0.1 mg/kg bwt, i.v.) resulted in tranquilisation and mild sedation (SS values of 1 and slight but significant decreases in HHAG) [10,13,14].…”

“…acepromazine dose of 0.05 mg/kg bwt was shown to achieve sedation in one study , a lack of sedation was reported by the same group of investigators in another study . However, those results should be interpreted cautiously as the former study evaluated sedation subjectively , while the latter study evaluated more specific parameters such as HHAG and a simple 4‐point descriptive sedation scale (SS), with scores from 0 (no sedation) to 3 (marked sedation) . Therefore, including an acepromazine treatment at a dose of 0.05 mg/kg bwt was justified in our study to confirm whether this drug results in sedation or not, as well as to determine whether acepromazine may allow the further reduction of xylazine doses to 0.25 mg/kg bwt.…”

“…Intravenous acepromazine alone (0.05 mg/kg bwt) did not produce sedative effects (no reductions in HHAG), confirming the results of Lizarraga et al . ; higher doses (0.1 mg/kg bwt, i.v.) resulted in tranquilisation and mild sedation (SS values of 1 and slight but significant decreases in HHAG) .…”

“…In situ: The main investigator (J.L.C. ), who was blinded to the treatment assessed degree of sedation by measuring the HHAG [7,[10][11][12][13][14]. The distance from the upper lip to the floor was measured in cm using a scale attached to the restraint-stock.…”

“…Currently, there is a tendency to avoid the use of subjective methodologies [8,9] and to include other parameters such as height of head above ground (HHAG) or sedation scoring systems that use simple descriptive scales (i.e. from 0, no sedation to 3, marked sedation) [7,[10][11][12][13][14].…”