Uterine and fetal asphyxia monitoring in parturient sows treated with oxytocin

Oxytocin is used to induce and control parturition, nevertheless, the increase of uterine contractions decreases blood flow and gaseous exchange through the womb predisposing to intra-partum mortality. The objective of the present study was to evaluate the effect of oxytocin on myometrial activity, fetal intrauterine hypoxia and postnatal asphyxia in sows during farrowing. Hybrid (n = 120) sows approaching the time of farrowing were randomly assigned in two groups of 60 animals each. Group I (G1: control) was treated IM with saline solution and Group II (G2) was injected IM with oxytocin (1 IU/6 kg LW) as a single dose at birth of the first piglet. Both average number of myometrial contractions and intensity in G2 were greater (P < 0.01) as compared with G1. The mean of intra-partum stillbirths (IPS's) and those where fetal cardiac frequency (FCF) or heart beats, could not be detected after birth, were greater (P < 0.01) in G2 as compared with G1. The average decelerations of FCF known as dips II, which indicate severe hypoxia, was greater in G2 (P < 0.01) as compared with that of G1. There was a greater (P < 0.01) number of intra-partum stillbirths, stained with severe meconium in G2 when compared with G1. Oxytocin treatment increased (P < 0.01) the number of pigs born alive with ruptured umbilical cords and those with different grades of meconium staining on their skin. It was concluded that administration of oxytocin at the onset of parturition increased the myometrial activity, decreased fetal cardiac frequency, predisposed the rupture of umbilical cords and the degree of meconium staining, and increased intra-partum mortality.