Castration of horses under total intravenous anaesthesia: analgesic effects of lidocaine.

The research investigates the benefits of using lidocaine as a local anaesthetic for castration in horses. The researchers found that using lidocaine reduces movements and number of incremental doses compared to a control group, demonstrating its efficacy in this context.

Methods

• The study was designed as a randomized, prospective, blinded clinical trial, meaning the individual administering treatment and those evaluating the results were ignorant of the treatment specifics.
• A group of 15 equidae, consisting of horses, donkeys, and ponies, were assigned at random to two groups. The lidocaine group consisted of 2 ponies, 4 horses, and 2 donkeys while the control group, which received saline injections, was composed of 2 ponies, 3 horses, and 2 donkeys.
• Prior to anesthesia, behavior, heart rate, and respiratory rate were evaluated. The animals’ body masses were measured and testicular volumes were estimated.
• Anesthetization was a two-step process starting with an intramuscular injection of acepromazine followed by an intravenous injection of romifidine 10 minutes later. After the application of romifidine, lidocaine or saline was administered via subcutaneous incision line injection and intratesticular and intrafunicular injection.
• The researchers used observational data (110 movement, f(R), and cranial nerve reflexes) to determine the need for incremental intravenous doses of ketamine and romifidine. Data such as heart rate, respiratory rate, average arterial blood pressure, duration of surgery, movement, and additional doses were recorded.
• The quality of surgical conditions was evaluated using a visual analogue scale (VAS) and a simple descriptive scale (SDS).
• The recovery process was monitored by two assistants, who were unaware of the treatment specifics, utilizing a VAS and a SDS.

Results

• The results showed that the lidocaine group required fewer incremental doses (median of 4 versus 1.5) and had fewer movements (median of 1 versus 0) than the control group. These differences were statistically significant (p = 0.01).
• Other variables that were recorded did not show any significant differences between the groups.

Conclusions

• The study concludes that lidocaine is effective when used as an adjunct to intravenous anesthesia in horses undergoing castration. The use of lidocaine was associated with fewer movements and a reduced requirement for additional doses of anesthetic compared to the control group.
• The study did not report any adverse effects associated with the use of lidocaine for castration, which further supports its safety and effectiveness for this procedure.