Intrauterine administration of plant oils inhibits luteolysis in the mare.

The research explores how the insertion of plant oils (like coconut or peanut oil) or oestrogen into the uterus of a horse can inhibit luteolysis, potentially changing the process of recognizing pregnancy and suppressing unwanted oestrous behavior.

Research Objectives and Methods

• The objective of the research was to investigate the effects of intrauterine administration of both estrogen and different types of oils on cyclic luteolysis in mares.
• The research hypothesizes that the introduction of oestradiol or fatty acids during the late stages of dioestrus could suppress luteolysis.
• A method they adopted includes a single 1 ml dose of slow-release oestradiol in fractionated coconut oil, infused into the uterine lumen of cycling mares on various days post ovulation.
• Four additional groups each comprising of 12 mares, received an intrauterine infusion of one of the following: fractionated coconut oil only, peanut oil only, mineral oil only or a slow-release preparation of oestradiol in mineral oil on the 10th day after ovulation.
• The luteal function of each mare was then monitored by assessing the progesterone concentrations in series of blood samples drawn from the mares.

Results of the research

• Intrauterine administration of oestradiol mixed in fractionated coconut oil showed optimal effectiveness on the 10th day post ovulation when luteolysis was delayed in 92% of the mares.
• When given on other days of dioestrus, the treatment’s luteolysis-delaying potential was less significantly pronounced but significantly dropped when administered on the 6th day post ovulation.
• The results show that oestradiol didn’t need to begin luteostasis because fractionated coconut oil or peanut oil administered on the 10th day post ovulation had a similar high rate of persistent luteolysis.
• In contrast, mineral oil did not extend the lifespan of the corpus luteum when administered alone or in combination with oestradiol.

Conclusions of the research

• The findings suggest that plant oils can delay luteolysis, which implies that they might modulate the synthesis or release of prostaglandins from the mare’s endometrium.
• Although the results don’t completely eliminate the possible involvement of embryonic estrogens in maternal recognition of pregnancy in mares, they suggest that it’s unlikely.
• The research concludes that the administration of fractionated coconut oil or peanut oil on the 10th day post ovulation provides an effective and practical method of extending luteal function and suppressing unwanted oestrous behavior.
• Further research could give more insight on the mechanism that makes this possible which would subsequently increase our understanding of luteostasis and MRP signals in mares.