A modified aglepristone protocol for mid-pregnancy termination in large dogs

Abstract

BACKGROUND-AIM Aglepristone, a competitive progesterone antagonist, is one of the available drugs to effectively terminate midpregnancy in dogs. The recommended protocol consists of two subcutaneous injections of Aglepristone (SC) at 10 mg/ kg of body weight administered 24 hours apart (Thomas & Fontbonne, 2008). A week later, animals are submitted to an ultrasound examination to confirm abortion. If not achieved, the protocol should be repeated. The reported effectiveness of Aglepristone-induced abortion at midpregnancy is close to 95% (Thomas & Fontbonne, 2008). In the practice, however, failure to abort after one cycle of Aglepristone at mid-pregnancy seems to be higher. In our experience, we perceived it as higher in larger-sized female dogs bearing large litters, driving the need for an additional cycle. That uncertainty on the success of the treatment in particular situations leads us to test an alternative, Aglepristone-modified protocol. METHODS The Aglepristone-modified protocol was tested in 10 healthy female dogs presented for pregnancy termination at a private clinic. The day of breeding and the embryonic morphology were used to estimate the age of the pregnancy. Aglepristone was administered at 10 mg/ kg on days 1 (at presentation), 3, and 5. Ultrasound was performed on day 12 to evaluate the response to the treatment. Data from these females were compared with retrospective data from the clinic, using a group of 10 midpregnancy female dogs treated for mismating with similar ages and size. RESULTS The age of the females submitted to the new protocol ranged between 10 months and 4 years old, and body weight between 28.2 to 37.6 kg. Unwanted pregnancies were estimated between 28 and 30 days, and all presented a large number of fetuses (between 8 and 11). The use of the modified Aglepristone protocol successfully interrupted pregnancy in all the cases with one cycle treatment, compared with a 70% success rate obtained with the standard protocol. CONCLUSIONS Preliminary results show that in large-sized bitches bearing larger litters, the aglepristone protocol described herein may be more efficient to induce abortion than the traditional one.