Effect of intratesticular injection of lidocaine on cardiovascular responses to castration in isoflurane-anesthetized stallions.

The research article explores the impact of anesthetic lidocaine’s intratesticular injection on cardiovascular responses and muscular tension during the castration procedure in horses under isoflurane anesthesia. The study concludes that injecting lidocaine into the testes prior to castration can reduce intraoperative blood pressure and cremaster muscle tension, suggesting the potential benefits of this method as a supplement to isoflurane anesthesia.

Research Methodology

• The research was carried out on 28 healthy stallions with an average age of about four years who had been scheduled for castration.
• Before the anesthesia, each horse was administered acepromazine, romifidine, and butorphanol to help manage pain and anxiety.
• Anesthesia was induced using ketamine and midazolam, while isoflurane was used for its maintenance.
• After ensuring a stable anesthetic plane, a needle was inserted in each testicle of the subject. Here, they either received an injection of 15 mL of 2% lidocaine or no fluid as a control.
• Castration started 10 minutes post the needle placement, during which the pulse rate and arterial blood pressures were closely monitored, recorded at 5 minute intervals before, during, and after the procedure.
• The surgeon noted the cremaster muscle tension throughout the procedure subjectively.

Results of the Study

• The study observed a significant increase in the blood pressure measurements during the castration process compared to the baseline values.
• The administration of intratesticular lidocaine was found to decrease this elevated blood pressure response and also lessen the cremaster muscle tension.
• In two particular cases, autoradiography was used with lidocaine labeled with radioactive carbon (C(14)). It illustrated a broad distribution of lidocaine into the spermatic cord but showcased poor distribution into the cremaster muscle.

Study Conclusions

• The study concluded that the use of intratesticular lidocaine injection before castration seemed to decrease the intraoperative blood pressure responses and cremaster muscle tension.
• These results suggest that lidocaine could be a beneficial supplement to isoflurane anesthesia during the castration procedure in isoflurane-anesthetized stallions, potentially enhancing the safety and efficiency of the surgical procedure.