Postpartum uterine motility measurements in dairy cows retaining their fetal membranes

Postpartum uterine contraction variables were measured in 15 parturient Holstein dairy cows and heifers: 8 assigned to dexamethasone (DEX) treatment and 7 to control (CON) treatment. The DEX animals were induced to calve early with an injection of dexamethasone and estradiol benzoate, administered on days 270 to 274 of gestation. At this time, the CON animals were injected with sterile saline and allowed to calve at term. Six of the eight DEX animals and one of the seven CON animals retained their fetal membranes longer than 12 hours postpartum. The uterine contraction variables determined were: the number of contractions over a 10 minute period (C/10), the average amplitude of contractions (AMP), the average duration of contractions (DUR), Montevideo units (MONT) and Alexandria units (ALEX). Recordings were taken at 1 hour, 6 hours and 48 hours postpartum, for a period of 20 minutes each. The contraction variables were measured using a catheter which was fluid-filled and inserted into the pregnant horn and connected to a pressure transducer, amplifier and recorder. The data were analyzed in terms of DEX vs. CON animals and animals with retained fetal membranes (RET) vs. animals with a normal release (NRET). Treatment with dexamethasone and estradiol benzoate resulted in an increase in C/10 at 48 hours (P<.05). The AMP, MONT and ALEX variables were also higher in the DEX animals, as compared to controls at that time. Significant differences (P<.01) were observed at 48 hours postpartum between the RET and NRET animals in terms of AMP, MONT and ALEX variables, and at that time the RET animals had a higher rate of uterine contractility than the NRET animals. No significant differences in the amount of uterine work between either the DEX and CON animals or the RET and NRET animals were observed, at 1 and 6 hours postpartum. The treatment with dexamethasone and estradiol benzoate prolonged uterine motility up to 48 hours postpartum, and the retention of the fetal membranes was not a result of the lack of uterine contractility during the early stages postpartum.