Influence of induction of parturition on the neonatal acute phase response in foals

The objectives of the present study were to determine whether induction of parturition in mares at term with low doses of oxytocin (2.5 i.u. i.v. every 20 min) affected the incidence of peri-partum complications or inflammatory responses in the neonatal foal. Parturition was induced in 11 of 26 mares and the remainder foaled spontaneously. Serum concentrations of amyloid A (AA; an acute phase protein) were measured (with a commercial ELISA) from 0 to 72 h postpartum in 18 of the neonatal foals. The incidence of dystocia and premature placental separation was higher in induced mares (2 of 11 and 1 of 11 versus 0 of 15 and 0 of 15, respectively), whereas retained fetal membranes were more common in spontaneous foalings (2 of 15 versus 0 of 11). When abnormal foals were excluded (to decrease the influence of endogenous serum AA elevations), serum concentrations of AA increased to the same extent over time in foals with induced versus spontaneous parturition; foals with spontaneous parturition had a mean serum AA concentration of 7.8 μg/mL at birth that increased to a maximum of 58.9 μg/mL at 36 h; foals with induced parturition had a mean serum AA concentration of 5.4 μg/mL at birth that increased to a maximum of 41.4 μg/mL at 48 h. Baseline serum AA concentrations were lower in induced foals. We concluded that inducing parturition with low doses of oxytocin in mares at term did not affect (relative to spontaneous parturition) the temporal dynamics of serum AA concentrations in the normal foal in the first 72 h of life. However, the induction procedure may lead to complications during parturition that, if not detected early, could result in the development of an inflammatory response in the neonate.