ContentsThe objective of this study was to evaluate the efficacy of cloprostenol (CLO) or aglepristone (ALI) for pregnancy termination in queens at 21-22 and 35-38 days of gestation. Two experiments (EXP) were carried out to accomplish this aim. Thirty-seven 12-to 14-month-old mixed breed queens were used in a randomized design. At oestrus, queens were housed for mating with a tom, and pregnancy was confirmed by transabdominal ultrasonographic examination (US). On days 21-22 of pregnancy (EXP1) or 35-38 of pregnancy (EXP2), queens were divided into three groups (G). Queens in G1 received ALI (10 mg/kg, sc; EXP1, n = 6; EXP2, n = 6) on two consecutive days. Queens in G2 received CLO (5 lg/kg, sc; EXP1, n = 6; EXP2 = 7) on three consecutive days. Queens in G3 received 1 ml of saline solution (PLA, sc; EXP1, n = 6; EXP2 = 6). After treatment, females were monitored daily by US during for 10 days and weekly until the end of gestation. In EXP1, pregnancy was terminated in (6/6, 100%), (0/6, 0%) and (0/6, 0%), for the ALI, CLO and PLA groups, respectively (p < 0.001). In EXP2, pregnancy was terminated in (6/6, 100%), (1/7, 14%) and (0/6, 0%) for the ALI, CLO and PLA groups, respectively (p < 0.001). In both EXP, after CLO administration, animals vomited and were depressed for 30 min; but no side effects were observed in the animals in the ALI group. In conclusion, the results from this study indicate that three injections of CLO are not effective, but two injections of ALI are effective to induce abortion in queens at 21-22 or 35-38 days of pregnancy.
IntroductionTermination of unwanted pregnancies in the queen can be achieved using cabergoline alone or in combination with prostaglandin F 2a (PGF;Onclin and Verstegen 1997;Eru¨nal-Maral et al. 2004). Previous studies have shown that multiple doses of PGF in cats from day 21 to day 25 of pseudopregnancy depressed luteal function, but did not produced complete luteolysis of the corpus luteum (Shille and Stabenfeldt 1979). Prostaglandins have been proved effective to induce abortion in queens with more than 40 days of gestation, but failed to induce abortion in queens with <40 days of pregnancy (Nachreiner and Marple 1974). It is not clear whether the effect of PGF in these animals was the result of direct abortifacient action on the uterus or because of luteolysis of the corpora lutea of pregnancy. It is possible that abortions occurred because of a direct contractile effect on the uterus in the presence of depressed luteal function, but complete luteolysis did not happen (Shille and Stabenfeldt 1979). Furthermore, when PGF was administered at 45 days of gestation, a higher percentage of abortion was obtained compared when it was used at day 30 of gestation. All cats had decreasing P 4 concentrations during treatment, but only queens with abortion showed P 4 levels <1 ng/ml (Baldwin et al. 2000). In addition, PGF administration at day 33 of pregnancy induces luteolysis and pregnancy termination with expulsion of foetuses (Verstegen et al. 1993). Furthermore, PGF and clop...