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

The anti-nociceptive effects of 50 mug kg(-1) of intramuscular xylazine wer e examined in seven lambs of 4-6 weeks of age using an electrical nocicepti ve testing method. Lamb anti-nociception increased from an average baseline of 5.88+/-0.72 mA to an average peak value of 13.662+/-1.49 mA at 21 minut es (mean+/-SEM) after the dose, and remained above baseline for the duratio n of the experimental period (60 minutes). All values were significantly ab ove baseline from 5 minutes post-xylazine administration onwards. These dat a were also compared with previously published data from adult sheep underg oing the same treatment. There were no differences in the analgesic respons e between the adult or lamb groups suggesting xylazine dose requirements sc ale with bodyweight and are unaffected by age over this range. These findin gs support the use of xylazine as an effective analgesic in sheep with comp arable effects and consistent dosing requirements per unit body weight betw een adult sheep and lambs. (C) 2001 Harcourt Publishers Ltd.