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

Objective-To determine whether administration of a microdose of prostagland in at the BAI HUI acupuncture point offers any advantage over IM injections for luteolysis, ovulatory interval, or systemic response in mares. Animals 17 mature cycling mares, 3 to 20 years of age and weighing 400 to 5 00 kg. Procedure-Conventional and microdoses of the prostaglandin dinoprost tromet hamine (PGF(2 alpha)), the analogue cloprostenol, or sterile water (control ) were administered to mares in 7 treatment groups. Treatments were assigne d by dose, administration site (semimembranosus, semitendinosus, or lumbosa cral region), and treatment type (PGF(2 alpha), analogue, or sterile water) . Mares were observed for ovulatory interval and systemic response to treat ment, including heart, and respiratory rates, rectal temperature, and sweat score. Plasma progesterone concentrations were also determined at the time of treatment and at 24-hour intervals for 96 hours following treatment. Results Ovulatory interval was shortened and progesterone concentrations de creased in prostaglandin-treated mares, compared with control mares, regard less of dose or treatment site. However, no differences in ovulatory interv al were observed among prostaglandin-treated mares. Mares treated with conv entional doses of PGF(2 alpha) had greater systemic responses than mares tr eated with microdoses of PGF(2 alpha) Or sterile water. Conclusions and Clinical Relevance-Administration of prostaglandins at the BAI HUI acupuncture point does not appear to offer any advantage over admin istration at standard IM injection sites for induction of luteolysis or to shorten the ovulatory interval. However, administration of a microdose of t he analogue cloprostenol was effective at inducing luteolysis and shortenin g ovulatory interval regardless of administration site.