Comparison of intraoperative pain responses following intratesticular or mesorchial injection of lidocaine in standing horses undergoing laparoscopic cryptorchidectomy.

The research tested pain responses in horses undergoing a specific type of surgery for cryptorchidism by using two different methods of administrating lidocaine as an anesthetic. The results suggested that either method combined with other measures provided adequate pain management for the horses.

Methods

• The research was a clinical trial with 20 stallions suffering from cryptorchidism, a condition where one or both of the testes fail to descend.
• The horses were given an anti-inflammatory drug and an epidural injection of detomidine, an anesthetic and analgesic, while in a standing position for laparoscopic cryptorchidectomy, a surgical procedure to remove the undescended testes.
• The researchers determined the level of pain response (i.e., present or absent) as well as the severity of pain by using a visual analog scale (VAS) when the undescended testis was held.
• Either the testis or its mesorchium, the connective tissue, was injected with lidocaine, while saline solution was injected in the structure left untreated.
• Two individuals determined the presence and severity of pain at various stages: after infiltration, at ligature placement, and at transection of the spermatic cord. The spermatic cord is a bundle of nerves, ducts, and blood vessels connecting the testicles to the abdominal cavity.
• For further analysis, serum cortisol levels were measured preoperatively, after ligation, and after transection. Cortisol is a hormone that increases in response to stress and low blood-glucose levels.

Results

• Both observers did not find any variance in detecting signs of pain and pain scores used during the VAS assessment at any point in time.
• The detected pain responses were significantly different from the pain responses before the operation when the ligature was being placed.
• No observable differences were seen in pain responses and serum cortisol levels, regardless of whether lidocaine was injected intratesticularly or into the mesorchium.

Conclusion

• The results of the study indicate that lidocaine, when administered either intratesticularly or on the mesorchium, combined with a nonsteroidal anti-inflammatory drug and a caudal epidural injection of detomidine, provides adequate pain relief in standing stallions undergoing laparoscopic cryptorchidectomy.