Induction of abortion in the bitch with a synthetic prostaglandin analog

Eight mixed-breed bitches in the middle (30 to 35 days) and late 3rd (53 to 56 days) of gestation were given 20 microg of synthetic prostaglandin analog/kg of body weight, IM (4 bitches) or the polyethylene glycol vehicle, IM (4 bitches). Bitches treated with prostaglandin aborted 2 days after treatment, whereas bitches given the vehicle delivered live pups at term. Luteolysis occurred within 24 hours of treatment, as shown by rapidly declining plasma progesterone concentrations. Microscopic signs of luteal degeneration were seen in ovaries removed 5 days after treatment. Three bitches erroneously designated as pregnant were treated during anestrus and had no marked changes in plasma progesterone or in gross and microscopic appearance of the reproductive tract. Serum alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase activities were increased slightly in 4 bitches on the day after treatment, but values declined to base-line values 24 hours later. Treatment side effects included panting, salivation, vomiting, repeated defecation, and transient pain at the injection site.