The anti-nociceptive efficacy of low dose intramuscular xylazine in lambs

The anti-nociceptive effects of 50 microg kg(-1)of intramuscular xylazine were examined in seven lambs of 4-6 weeks of age using an electrical nociceptive testing method. Lamb anti-nociception increased from an average baseline of 5.88+/-0.72 mA to an average peak value of 13.66+/-1.49 mA at 21 minutes (mean+/-SEM) after the dose, and remained above baseline for the duration of the experimental period (60 minutes). All values were significantly above baseline from 5 minutes post-xylazine administration onwards. These data were also compared with previously published data from adult sheep undergoing the same treatment. There were no differences in the analgesic response between the adult or lamb groups suggesting xylazine dose requirements scale with bodyweight and are unaffected by age over this range. These findings support the use of xylazine as an effective analgesic in sheep with comparable effects and consistent dosing requirements per unit body weight between adult sheep and lambs.