Comparison of intraoperative behavioral and hormonal responses to noxious stimuli between mares sedated with caudal epidural detomidine hydrochloride or a continuous intravenous infusion of detomidine hydrochloride for standing laparoscopic ovariectomy.

This research studies pain, relevant behavior, and hormonal responses in horses undergoing a surgical procedure called laparoscopic ovariectomy when sedated with two different methods. It was found that both continuous intravenous (IV) and epidural detomidine sedation yielded similar results.

Research Setup

• The study was conducted in a double blind manner to reduce bias.
• 12 mares were included in the research and were split into two treatment groups. One group received continuous IV detomidine infusion for sedation while the other group was sedated using epidural detomidine.
• All horses were given the same premedication consisting of IV xylazine and butorphanol tartrate before detomidine was administered.
• The procedure performed on the animals was a standing laparoscopic ovariectomy – a minimally invasive surgical operation to remove the ovaries.

Methodology for Observations and Measurements

• At four different time points: upon arrival, 10 minutes prior to surgery, after the removal of the second ovary, and 10 minutes after the surgery, venous blood samples were collected from the mares to measure cortisol levels. Cortisol is a hormone that increases in response to stress and pain.
• During 8 instances involving surgical manipulations, two surgeons individually noted whether the animal showed pain (yes/no).
• A visual analogue scale (VAS) of 0 to 10 was used for measuring the severity of the pain response, where 0 indicated no pain responses and 10 indicated severe pain that necessitated additional sedation or analgesia. Each horse was also assigned an overall VAS score by each surgeon to grade their satisfaction with the analgesic effects during the entire procedure.

Results

• The comparison of cortisol levels revealed significant differences in the baseline measurements between the two groups. However, there were no significant differences at the other three time points.
• The VAS scores for 7 of the procedures didn’t show significant differences between the two groups.
• A notable difference was observed in the initial grasp of the left ovary in the group sedated with continuous IV infusion. This group had a significantly higher median VAS score compared to the group sedated with epidural detomidine.

Conclusions

• The study concluded that the hormonal and behavioral responses to painful stimuli were very similar in horses sedated with either epidural or continuous IV detomidine during a standing laparoscopic ovariectomy.
• The researchers therefore suggest that the use of a continuous IV infusion of detomidine can be an effective method for sedation during this procedure.