The effects of cervical dilation on plasma PGFM, progesterone and the duration of luteal function in diestrous mares.

This research investigates whether cervical dilation procedures, commonly used in veterinary diagnostics, impact the luteal function and hormonal levels in mares during their estrous cycle. The study concludes that cervical dilation doesn’t affect luteal function or the levels of certain hormones, however, the use of a prostaglandin synthetase inhibitor prior to doing so does reduce hormone concentrations in the horses.

Research Design

• The study involved nine mares that were examined to determine the impact of cervical dilation on their progesterone (P(4)) levels, plasma 13,14-dihydro-15-keto-prostaglandin F(2) levels (PGFM), and the subsequent duration of their luteal function.
• The subjects were given a daily score of 0 to 4 based on their sexual receptivity; five days after the end of this period, each horse was randomly assigned to one of three treatment groups.

Treatment Groups

• The first group, the control group, did not undergo any cervical dilation procedures.
• The second group, known as the cervically stimulated group, had their cervixes dilated for 60 seconds.
• The third group, the cervically stimulated plus inhibitor group, underwent the same dilation procedure but were also administered a prostaglandin synthetase inhibitor thirty minutes prior to the dilation.
• Each horse experienced all three treatments over the course of their three consecutive estrous cycles.

Findings and Conclusions

• Results of the experiment showed lower levels of plasma PGFM in the group that received the inhibitor before dilation, in comparison to the control and the cervically stimulated groups.
• Slightly lower levels of progesterone were also recorded in this group.
• Importantly, there were no differences observed in the duration of luteal function between any of the three groups.
• This suggests that cervical dilation itself does not affect plasma PGFM and P(4) levels, or the duration of luteal function. However, the administration of a prostaglandin synthetase inhibitor before cervical dilation was shown to decrease plasma PGFM and P(4) concentrations.