Meclofenamic acid extends donor-recipient asynchrony in equine embryo transfer.
Authors: Wilsher S, Kölling M, Allen W R
Journal: Equine veterinary journal
Summary
# Editorial Summary: Meclofenamic Acid and Embryo Transfer Asynchrony Establishing pregnancy via embryo transfer requires precise synchronisation between the developmental stage of the embryo and the physiological readiness of the recipient mare's uterus; however, practical constraints often create timing mismatches that reduce success rates. Wilsher and colleagues investigated whether meclofenamic acid—a non-steroidal anti-inflammatory drug that inhibits prostaglandin synthesis—could extend the window of acceptable asynchrony by suppressing luteolysis and prolonging the corpus luteum's functional lifespan. Seventy-two high-quality embryos were transferred into recipients ovulating 2–5 days before the donors, with half receiving oral meclofenamic acid (1 g daily from day 9 post-ovulation for 7 days post-transfer) and half serving as controls. At a 3-day asynchrony, treated mares achieved significantly higher pregnancy rates (80%) compared to untreated controls (20%), though pregnancy rates declined progressively with greater asynchrony; surprisingly, luteolysis occurred at normal timing in both groups, suggesting the drug's benefits operated through mechanisms other than prolonging corpus luteum function. For practitioners, this research demonstrates that meclofenamic acid can meaningfully improve embryo transfer outcomes when recipients ovulate moderately ahead of donors, though the mechanism warrants further investigation and the drug's effect diminishes substantially beyond 3 days of asynchrony.
Read the full abstract on PubMed
Practical Takeaways
- •Oral meclofenamic acid (1g daily for 7 days post-transfer) can be used to improve pregnancy success when recipient mares ovulate 3 days before embryo donors, increasing practical flexibility in ET scheduling
- •The window of acceptable asynchrony can be widened to ±3 days with meclofenamic acid treatment, improving the efficiency of recipient mare utilization on breeding operations
- •Do not expect meclofenamic acid to rescue embryo transfers with >3 days asynchrony, as pregnancy rates remain low even with treatment at +4 or +5 days
Key Findings
- •Meclofenamic acid improved pregnancy rates in recipient mares ovulating 3 days before donors (80% vs 20%, P=0.025)
- •Treatment supported pregnancy establishment at +3 days asynchrony but not at +4 or +5 days asynchrony
- •Meclofenamic acid's beneficial effect did not occur through suppression of luteolysis, as corpus luteum regressed normally in both treated and untreated non-pregnant mares
- •At +2 days asynchrony, pregnancy rates were similar between treated and untreated groups (90% vs 80%, P=1.00)