[Experiences with the use of xylazine for sacral epidural anesthesia in cattle]

The effect of epidural administered xylazine was investigated in 10 mature Holstein cows (mean age: 5.4 +/- 1.2 years, mean BW: 572 +/- 23 kg): 5 cows were treated with xylazine in a low dose of 0.05 mg/kg body weight, 3 cows in a medium dose (0.07 mg/kg BW) and 2 cows in a high dose (0.1 mg/kg BW). Xylazine dosages were diluted in sterile saline to a final volume of 5 ml. As a control, lidocaine (5 ml of a 2% solution) was given to 5 cows epidurally. Duration of regional anaesthesia after low dose of xylazine (0.05 mg/kg BW) was significant longer (mean: 2.2 hours) compared to lidocaine treated cows (mean: 1.1 hour). Regional extension of anaesthesia was comparable after dosing with xylazine and lidocaine (tail, after, vulva and perineum). All cows remained standing, but in xylazine treated cows systemic effects, e.g. mild sedation, decreased heart- and respiratory rates, decreased rumen motility and mild bloat were observed. With increased dosages of xylazine a prolongation of epidural anaesthesia up to 3 hours was achieved, but regional extension of this effect remained nearly unchanged. With increased xylazine dosages, cows showed marked sedation and ataxia and sternal recumbency were induced.