Influence of caudal epidural analgesia on cortisol concentrations and pain-related behavioral responses in mares during and after ovariectomy via colpotomy.
Authors: Rowland Aileen L, Glass Kati G, Grady Sicilia T, Cummings Kevin J, Hinrichs Katrin, Watts Ashlee E
Journal: Veterinary surgery : VS
Summary
# Caudal epidural analgesia for ovariohysterectomy in mares: efficacy and cortisol response Ovariectomy via colpotomy is a painful procedure, yet optimal perioperative analgesia protocols for mares remain unclear. Rowland and colleagues conducted a blinded prospective study comparing caudal epidural detomidine (0.01 mg/kg) and morphine (0.1 mg/kg) administered pre-operatively against systemic butorphanol (0.02 mg/kg IV) repeated every 4 hours for 24 hours post-operatively in nine university mares, measuring serum cortisol concentrations at multiple time points and assessing pain-related behaviours including leg lifting, grunting, grimace scale scoring, and heart rate throughout the procedure and recovery period. The epidural group showed no significant differences in cortisol concentrations, heart rate, or pain-related behavioural responses compared to the systemic opioid group, though phenylbutazone administration (given 18 hours post-operatively to all horses) resulted in measurable reductions in grimace scale scores across both groups. A single pre-operative epidural dose of detomidine and morphine appears to provide analgesia equivalent to repeated systemic butorphanol dosing, suggesting it may reduce the need for frequent opioid administration whilst maintaining consistent pain control and neuroendocrine stability following ovariohysterectomy. For practitioners managing post-operative mares, this approach warrants consideration as a viable alternative, though careful individual assessment of pain indicators and response remains essential.
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Practical Takeaways
- •Single caudal epidural injection of detomidine and morphine provides equivalent pain relief to repeated IV butorphanol dosing over 24 hours post-ovariectomy, simplifying pain management protocols
- •Epidural analgesia may reduce total opioid load while maintaining adequate pain control, which could be valuable for managing post-surgical mares with reduced handler stress
- •Consider caudal epidural analgesia as an alternative to frequent systemic opioid administration for ovariectomy procedures, particularly when repeated handling for medication is undesirable
Key Findings
- •Caudal epidural detomidine (0.01 mg/kg) and morphine (0.1 mg/kg) produced equivalent pain control to systemic butorphanol (0.02 mg/kg IV every 4 hours) for 24 hours post-ovariectomy
- •No significant differences in serum cortisol concentrations between epidural and systemic opioid groups during and after surgery
- •Horse grimace scale scores decreased following phenylbutazone administration at 18 hours postoperatively
- •Epidural analgesia may reduce the need for frequent systemic opioid dosing after painful procedures