Short-term anaesthesia with xylazine, diazepam/ketamine for castration in horses under field conditions: use of intravenous lidocaine.

This study aims to determine the effects of using lidocaine as an adjunct with xylazine-diazepam/ketamine anesthesia for horse castration in field conditions. The findings suggest that while lidocaine does not impact recovery negatively, it does not lower the need for additional injectable anesthetics and prolongs the overall recovery period.

Objective of the Study

• The researchers sought to examine the impact of systemic lidocaine on the administration of xylazine-diazepam/ketamine anaesthesia for castration in horses, particularly in field settings. The study was primarily concerned with whether this combination would decrease the need for additional injections to maintain the effect, and how the addition of lidocaine would influence the recovery process and outcome.

Methodology

• The study involved 30 client-owned horses, all undergoing castration under field conditions with standard injectable anesthesia. Among them, 15 received a single bolus of lidocaine at 3 mg/kg body weight intravenously, while the other 15 received an equivalent volume of saline.
• The horses were monitored to assess their requirement for additional anesthetics during the procedure. Their recovery, both in terms of score and quality, was evaluated by an anaesthetist who was not privy to the specifics of each horse’s treatment (blinded).

Results and Findings

• The study found no statistically significant difference in the recovery score and quality, or the requirement for additional anesthetics, between the lidocaine and saline groups. However, horses treated with lidocaine took a notably longer time to stand after induction: 30.7 minutes on average, versus 22.5 minutes in the saline group. This difference was statistically significant.

Conclusions and Implications

• The study concluded that adding lidocaine to injectable anesthesia in field conditions does not adversely affect recovery, although it does extend the overall recovery period. Lidocaine may not be an effective means of reducing the need for supplementary anesthetic administrations.
• Based on these results, the researchers recommended further exploration of the utility of systemic lidocaine in field anesthesia for horses. They suggested that future studies should aim to ascertain the most advantageous dose and plasma level when pairing lidocaine with injectable anesthesia.