The Combination of hCG and GnRH Analog to Hasten Ovulation in Mares Does not Change Luteal Function and Pregnancy Outcome in Embryo Recipient Mares.

This study examines whether combining hCG and deslorelin acetate can speed up ovulation in mares more effectively than using either drug on its own, and if the combination impacts the mares’ luteal function and pregnancy outcomes. It concludes that while the use of these drugs can hasten ovulation, it does not significantly alter luteal development or pregnancy outcome.

Research Methodology

• The study involved 17 mares whose ovulation was speeded up with combinations of treatments: a control group receiving a saline solution (NaCl); one group treated with 1 mg of deslorelin acetate (GnRH); another with 1500 IU of hCG; and one group treated with a combination of 1mg of deslorelin acetate and 1500 IU of hCG.
• Data was gathered on corpus luteum (CL) diameter and blood flow, and serum progesterone concentrations between the day of ovulation induction and sixteen days afterward.
• In addition, data from 194 embryo transfers were retrospectively analyzed, comparing pregnancy rates and instances of pregnancy loss in mares with naturally induced ovulation (Control), and those induced with hCG, deslorelin acetate, or the combination of these hormones.

Results and Conclusions

• The control group showed higher progesterone concentration on the day of ovulation than the GnRH group. However, the levels of progesterone concentration varied over time and showed no significant differences.
• There were no differences in CL diameter and blood flow at any point in the study, demonstrating that neither drug, nor the combination of the two, affected luteal function.
• Pregnancy rates and instances of pregnancy loss did not differ between mares treated with hormones and those that were not, suggesting that the combined use of hCG and deslorelin acetate does not affect pregnancy outcomes.
• The study concluded that while the combination of hCG and deslorelin can certainly speed up ovulation, it does not significantly influence luteal development, progesterone concentrations, or pregnancy outcome in mares following embryo transfer.