Epidural morphine and detomidine decreases postoperative hindlimb lameness in horses after bilateral stifle arthroscopy.

This research study investigates the effect of preoperative administration of certain drugs on postoperative lameness in horses undergoing bilateral stifle arthroscopy. The findings suggest preoperative epidural applications of morphine and detomidine can significantly reduce lameness and heart rate after surgery.

Study Objectives and Design

• The primary objective of this study was to determine if preoperative administration of epidural morphine and detomidine could reduce postoperative lameness in horses undergoing bilateral stifle arthroscopy.
• The study was a prospective clinical controlled study involving eight adult horses that had bilateral arthroscopic procedures, which included drilling of cartilage and subchondral bone within the femoropatellar joints.

Methodology

• The horses were randomly separated into two groups. Four horses were administered a combination of epidural morphine (0.2 mg/kg) and detomidine (30 microg/kg), and four horses received an equivalent volume of epidural saline (0.9% NaCl) solution preoperatively.
• Postoperative pain was assessed using six video recordings made at hourly intervals of each horse at a walk, starting one hour after recovery from anesthesia.
• Three observers, who were not aware of the treatment groups, evaluated the recordings. They scored lameness from 0 to 4.
• The lameness scores of the two groups of horses were compared using a Wilcoxon’s rank sum test. Heart rates and respiratory rates were also measured at each hour, and their differences between groups were evaluated using a repeated-measures ANOVA. Statistical significance was set at P < .05.

Results

• The findings indicated that horses preoperatively administered with epidural morphine and detomidine experienced significant decreases in lameness and heart rate after bilateral stifle arthroscopy. Notably, the largest decrease was noticed at hours 1 and 2 following recovery from anesthesia.

Conclusions

• The researchers concluded that horses undergoing painful arthroscopic procedures of the stifle joint can benefit from preoperative administration of epidural morphine and detomidine.
• The study suggests that these medications potentially can be beneficial in reducing postoperative pain after stifle arthroscopy, along with managing pain associated with other painful disorders involving the stifle joint, including septic arthritis and trauma.