Luteal and clinical response following administration of dinoprost tromethamine or cloprostenol at standard intramuscular sites or at the lumbosacral acupuncture point in mares.

This research paper studied the effectiveness of injecting a microdose of prostaglandin at the BAI HUI acupuncture point versus the standard intramuscular sites in mares. The study found no evident advantage of either method in inducing luteolysis or shortening the ovulatory interval.

Objective and Methodology of the Study

• The intention of the research was to ascertain whether using a microdose of prostaglandin at the BAI HUI acupuncture point has any advantage over intramuscular (IM) injections in causing luteolysis, shortening ovulatory interval, or causing systemic responses in mares.
• The study was performed on 17 mature cycling mares, aged 3 to 20 years and weighing between 400 to 500 kg.
• Two kinds of prostaglandin, dinoprost tromethamine (also known as PGF2alpha) and a cloprostenol analogue, were used in the experiment, alongside a sterile water control.
• The mares were divided into seven groups for treatment. The groups were differentiated based on the dose (either conventional or microdose), administration site (semimembranosus, semitendinosus, or lumbosacral region), and the type of treatment (PGF2alpha, analogue, or sterile water).

Observations and Measurements

• Researchers observed the mares for ovulatory interval and systemic response to treatment. This included heart, respiratory rates, rectal temperature, and sweat score.
• Plasma progesterone concentrations were determined at the time of treatment and at 24-hour intervals for 96 hours following treatment.

Results of the Study

• The study found that the ovulatory interval was shortened and progesterone concentrations decreased in prostaglandin-treated mares, irrespective of the dose or treatment site, compared to control mares.
• No differences in ovulatory interval were observed among prostaglandin-treated mares.
• Sytemic responses were greater in mares treated with conventional doses of PGF2alpha compared to mares given microdoses of PGF2alpha or sterile water.

Conclusions from the Study

• Based on the results, the researchers concluded that administering prostaglandins at the BAI HUI acupuncture point does not seem to provide any advantage over standard IM injection sites in inducing luteolysis or shortening the ovulatory interval.
• They also concluded that administering a microdose of the cloprostenol analogue was effective at inducing luteolysis and shortening the ovulatory interval regardless of the administration site.