Prostaglandin induction of abortion in pregnant bitches after misalliance

Of 48 privately-owned bitches evaluated 30 to 35 days after a single, unplanned breeding, 30 (62%) dogs were determined not to be pregnant by abdominal ultrasonography and 18 dogs were confirmed to be pregnant. Each pregnant dog was hospitalized, allotted to a treatment group, and given prostaglandin F2 alpha, SC, at 1 of 3 dosages: group 1, 0.1 mg/kg of body weight, every 8 hours; group 2, 0.25 mg/kg, every 12 hours; and group 3, 0.1 mg/kg, every 8 hours for 2 days and then 0.2 mg/kg every 8 hours thereafter. Plasma from each dog was assayed for progesterone concentration before treatment and daily until abortion was completed. Physical examinations and abdominal ultrasonography were performed every 12 and 48 hours, respectively. Treatment was continued until abortion was complete as determined by results of abdominal ultrasonography. Ultrasonography was performed earlier than the scheduled 48 hours if abdominal contractions, fetuses, or bloody or dark colored vaginal discharge was observed. Dogs of 14 breeds were treated; body weight ranged from 5.4 to 37.7 kg. All dogs aborted all fetuses within 9 days of beginning treatment. Abdominal palpation was not satisfactory in confirming whether the abortion process had been completed; however, results of ultrasonography were a reliable indicator. Plasma progesterone concentrations prior to treatment were typical of the middle phase of gestation, with all concentrations > 6.0 ng/ml. The plasma progesterone concentration decreased significantly in each dog after the first 48 hours of therapy. None of the bitches aborted any fetal material until at least 24 hours after the plasma progesterone concentration was < 2.0 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)