L-Bupivacaine 0.5% vs. racemic 0.5% bupivacaine for caudal epidural analgesia in horses.

The research article explores the effects of two types of bupivacaine, an anesthetic, for caudal epidural analgesia in horses. It focuses on comparing the efficacy and safety of S(-)-bupivacaine (LB) and standard racemic bupivacaine (RB). The study concludes that there’s no significant difference in results between the two types, with LB showing potential as an effective alternative.

Study Objective and Method

• The aim of the study was to analyze the efficacy and safety of two variants of an anesthetic, bupivacaine, when used in caudal epidural analgesia in horses.
• The study was conducted in a randomized, double-blind manner meaning the assignation of the anesthetic type for each horse was random and neither the horses nor the administrators of the anesthetic knew which type was being given.
• Each horse received two treatments, with a gap of two weeks in between treatments. Treatment 1 involved the administration of 0.5% LB at a dose of 0.06 mg/kg of the horse’s body weight. Treatment 2 involved the administration of 0.5% RB at the same dosage.
• The administrations were given in the form of an epidural injection between the first and second coccygeal vertebra.

Data Collection and Results

• Several measurements were taken before and after the drug administration, including heart rate (HR), arterial pressures, respiratory rate (RR), rectal temperature (RT), level of analgesia (pain relief), and motor blocking (paralysis of the motor function).
• The measurements were taken at numerous time intervals: pre-administration, 5, 10, 15 and 30 minutes post-administration, and every 30 minutes thereafter.
• The research concluded that there was no significant difference between the two types of bupivacaine in terms of sensory and motor block quality.
• The duration of analgesia lasted 320 +/- 30 min for RB and 360 +/- 42 min for LB. There were no significant changes in HRs, RRs, arterial pressures and RT after the epidural administration of either type of bupivacaine.

Conclusion

• This study supported the effective use of 0.5% LB as an alternative to RB for caudal epidural analgesia in conscious, standing horses.
• The comparison of the use of LB vs. RB warrants further study, particularly for long-lasting surgery in the perineal region (area around the anus and genitals) of horses.