The effects of aglepristone alone and in combination with cloprostenol on hormonal values during termination of mid-term pregnancy in bitches

This study was designed to assess endocrine changes associated with termination of mid-term pregnancy after use of two different protocols. For this purpose we compared the effects of aglepristone (AGL) alone and in combination with cloprostenol (CLO) on serum concentrations of progesterone (P4), estradiol (E2) and relaxin (RLN) measured at short-term intervals during the abortion period in bitches. Fourteen pregnant bitches between day 25 and 32 of gestation were used in the study. In the AGL group (n = 7), aglepristone was administered solely (10 mg/kg body weight (BW), subcutaneously, once daily on two consecutive days) whereas in the AGL-CLO group (n = 7), aglepristone (dosage as in AGL group) and cloprostenol (1 μg/kg BW, subcutaneously, same with aglepristone) were combined. All pregnancies were successfully terminated 5.2 ± 1.6 days after initiation of treatments, which was significant in both groups (P > 0.05). At the time of the start of abortion (SA) and the end of abortion (EA), the mean P4 concentrations were 26.6 ± 7.3 and 12.0 ± 6.4 ng/ml in AGL group, and 2.7 ± 0.7 and 0.9 ± 0.1 ng/ml, in AGL-CLO group, respectively (P < 0.01). Serum E2 concentrations were significantly higher (P < 0.05) in AGL group at 42, 48, 54 h and SA after initiation of treatment. In the AGL-CLO group, serum RLN concentrations did not significantly change from the initiation of treatment to EA (P > 0.05). However, markedly higher RLN concentrations (P < 0.05) were observed in the AGL group at 48 h (1.5 ± 0.7 ng/ml) and at SA (1.6 ± 0.5 ng/ml). The results of the present study indicate that changes in the hormonal concentrations affect the mechanism of abortion in different ways. Further in depth studies investigating changes in the expression of hormone receptors inside the ovary, endometrium and placenta might be helpful to our understanding of the endocrinological differences observed in this study.