Efficacy and cardiorespiratory effects of lumbosacral intrathecal 2% procaine and 2% xylazine with or without sedation in calves undergoing umbilical surgery.

To compare the effects of intrathecal anaesthesia using procaine and xylazine, with and without sedation with I/V xylazine and butorphanol, on sedation and cardiorespiratory measures in calves undergoing umbilical surgery. Male dairy calves, aged <3 months, were recruited that had enlargement of the umbilical stalk which was abnormal when palpated. They were assigned to receive either intrathecal injection between the sixth lumbar and first sacral vertebrae of 4 mg/kg of 2% procaine and 0.2 mg/kg 2% xylazine, with I/V injection of 0.02 mg/kg xylazine and 0.1 mg/kg of butorphanol (IT + SED group; n = 6), or the same intrathecal injection and I/V injection of 0.9% saline (IT group; n = 7). Surgery to correct abnormalities was carried out with calves positioned in dorsal recumbency. Rescue analgesia with injections of 2% procaine around the surgical wound was administered when movements triggered by surgery were observed. Post-operative analgesia was provided using I/V 0.5 mg/kg meloxicam. Duration of surgery was recorded, as well as degree of sedation, heart rate, systolic (SAP), diastolic (DAP) and mean (MAP) arterial blood pressure during surgery. All anaesthetic and surgical procedures were successfully performed. Mean total duration of surgery was similar for the IT + SED and the IT groups (30.33 (SD 10.09) and 31.00 (SD 10.21) minutes, respectively) (p = 0.92). All calves were at least mildly sedated from 5 minutes after injections to the end of the surgery. One calf in the IT + SED group and three calves in the IT group required rescue analgesia when the umbilicus was manipulated. Between 0 and 10-15 minutes after injection, decreases in mean heart rate, SAP, MAP and DAP were observed in both groups. Mean SAP was lower in the IT + SED than the IT group. Hypotension (MAP<60 mm Hg) was present in four calves from the IT + SED group and in one from the IT group. Intrathecal administration of 2% procaine and 2% xylazine allowed the successful completion of umbilical surgery, but 30% of calves needed rescue analgesia during surgery. Clinically, the addition of I/V sedation seemed to provide better analgesia than intrathecal block alone but resulted in greater hypotension.