Effects of epidural administration of xylazine or lidocaine on bovine uterine motility and perineal analgesia

The objective of this study was to evaluate and compare the effects of caudal epidural (sacral-coccygeal interspace) administration of xylazine or lidocaine on uterine motility and perineal analgesia in the cow. Six Holstein cows (7 d post estrus) were assigned to one of three treatment groups: control (5 ml saline); lidocaine (0.2 mg/kg, 2% solution); and xylazine (0.06 mg/kg suspended in 5 ml saline), with each cow randomly assigned to each treatment over a period of three estrous cycles. Uterine motility, perineal analgesia, electrocardiography, and overt signs of sedation were recorded. Data were collected at 10-min intervals starting 10 min before treatment and continuing until 60 min post treatment. At 60 min post treatment, oxytocin (20 USP units) was administered i.v. to serve as a positive control for uterine motility. In the xylazine group, uterine motility significantly (P < 0.05) increased at 20 min post treatment, peaked at 30 min, and gradually decreased to non-significant levels at 50 min post treatment when compared with the lidocaine and control groups. Additionally, xylazine produced a higher degree and longer duration of perineal analgesia than lidocaine. Systemically, epidural xylazine produced signs of sedation, salivation, vocalization and bradycardia. Ataxia was also observed in the xylazine-treated group which may have been induced through a local and/or systemic effect. The individual properties of xylazine and lidocaine should be taken into consideration when performing an obstetrical procedure requiring the use of an epidural analgesic agent, and they should be utilized to benefit the clinician in performing the procedure.