Termination of mid‐term pregnancy in the dog with oral RU 486

Abstract

A total of four pregnancies were terminated in three bitches (two beagles and one flatcoated retriever) with a single dose of 20 mg/kg (one case), two doses of 8‐3 mg/kg (one case) or 20 mg/kg plus 40 mg/kg (two cases) RU 486 by mouth (Mifepristone; Roussel‐Uclaf, France) from day 26 to day 36 after the first day of mating of the bitch. Abortions occurred within two, four, 11 and 11 days after the initial treatment, respectively. The clinical status of the bitches was similar to that observed during a normal parturition, ie, lowering of the body temperature, shivering, panting and nesting behaviour. No side effects were seen. The beagle bitch that aborted twice, was mated at the first oestrus after the first abortion, conceived and aborted the same number of puppies the second time. The peripheral plasma progesterone concentration at the time of treatment in all bitches was < 75 nmol/litre. It had decreased to between 24‐2 and 13‐1 nmol/litre at the time of abortion and to between 4‐0 to 0–5 nmol/litre at four to 15 days after the initial treatment. Peripheral plasma levels of prolactin increased three‐ to fourfold within 24 to 48 hours after treatment, concomitant with the drop in progesterone and had returned to basal levels within two to three days. Prolactin concentrations also increased around the time of intrauterine fetal death. Prostaglandin F2aα‐metabolite concentrations increased slowly after treatment, and around the time of abortion the levels increased five‐ to 10‐fold. RU 486 seems to be a safe and effective abortifacient for use during mid‐term pregnancy in the dog.

Induction of Abortion with Aglepristone in Cats on Day 45 and 46 After Mating

“…A newer possibility is the use of antiprogestins that have been described in dogs and cats for pregnancy termination in the first and second trimester (Sankai et al. 1991; Linde‐Forsberg et al. 1992; Fieni et al.…”

“…Combined treatment with PGF 2a and cabergoline was more successful and side effects were significantly reduced but still observed (Onclin and Verstegen 1997;Eru¨nal-Maral et al 2004). A newer possibility is the use of antiprogestins that have been described in dogs and cats for pregnancy termination in the first and second trimester (Sankai et al 1991;Linde-Forsberg et al 1992;Fieni et al 1996Fieni et al , 2001Hubler and Arnold 2000;Gobello et al 2003;Georgiev and Wehrend 2005;Wehrend and Georgiev 2006), conservative treatment of pyometra (Blendinger et al 1997;Breitkopf et al 1997;Hecker et al 2000;Hoffmann et al 2000) and fibroadenomatosis Wehrend et al 2001;Sontas et al 2008). Although the application is easy and the risk for side effects is low, until now there is no data on the efficacy of aglepristone within the last trimester of pregnancy in the cat.…”

Induction of Parturition with Aglepristone in the Majorera Goat

“…Mifepristone (RU486) has shown its efficacy in pregnancy termination in the bitch (Concannon et al. 1990; Linde‐Forsberg et al. 1992) and the queen (Eilts 2002).…”

“…Progesterone-receptor blockers such as aglepristone and mifepristone are competitive antagonists of the progesterone receptors (Cadepond et al 1997;Baan et al 2008). Mifepristone (RU486) has shown its efficacy in pregnancy termination in the bitch (Concannon et al 1990;Linde-Forsberg et al 1992) and the queen (Eilts 2002). However, other studies were inconsistently successful in inducing parturition after the administration of mifepristone in bitches (Nohr et al 1993).…”

Placenta functions with special emphasis on endocrine changes – a comparative overview

“…Obviously, a luteolytic uterine derived factor is involved in the decline of progesterone. In the dog, several studies have been performed to induce abortion [9][10][11] or parturition [12].…”