A comparison of agents for inducing parturition in mares in the pre-viable and premature periods of gestation.

Various regimens of prostaglandins, alone or followed by oxytocin, were given to induce parturition in mares during the pre-viable and premature periods of gestation and in near-term mares. The most successful method of induction was found to be 2 i.m. injections of 500 micrograms fluprostenol (Equimate: I.C.I.) at a 2-h interval followed (if necessary) by 10-20 i.u. oxytocin injected i.v. in 5 i.u. serial increments every 15-20 min. Peak concentrations of the prostaglandin metabolite (PGFM) in response to the inducing agents were shown to be associated with delivery at, but not before, 320 days of gestation. A radiolabelled study of [14C]fluprostenol distribution showed that fluprostenol was present in placenta, amnion, allantoic and amniotic fluid, and in foal plasma and liver.