Luteolysis, estrus induction, and clinical side effects in mares treated with a PDF2α analog, cloprostenol (Sinocrel 11-21)

The objective of this study was to prove the effectiveness of cloprostenol, a synthetic prostaglandin analog for the induction of luteolysis in the mare, as well as to evaluate its clinical side effects. Twenty-five mares were treated on day 6 after ovulation with 0.075 mg cloprostenol. Blood samples were taken to determine plasma progesterone levels. Progesterone levels were below 1 ηg/mL at 42.2 ± 10.4 hours after treatment, which indicated that there was no longer a functional corpus luteum (CL). It was shown that in 96% (24/25) of the mares, the prostaglandin F2α (PGF2α) analog at the dose used had a luteolytic effect. All the mares showed estrous behavior within 5 days after application of the PGF2α analog. The prostaglandin treatment caused a significant increase (P < .01) in intestinal motility and subsequently a short-term diarrhea of 2 hoursʹ duration in 64% (16/25) of the mares. There was not a significant difference (P > .05) in the heart rate and the respiratory rate between the treated group and the control group.