Ultrasonography of the bovine postpartum uterus with retained fetal membranes.

The aim of this study was to describe the potential application of ultrasound in combination with the rectal palpation method and to compare the results to determine the involution period in 11 Swedish dairy cows with retained fetal membranes (RFM). The animals were examined three times a week during the first 8-week postpartum (PP) period. Significant quantity of abnormal vaginal discharges with concomitant accumulation of snowy fluid and thickening of the endometrial and uterine walls were interpreted as evidence of endometritis. The discharges decreased most markedly during the third week PP concomitantly with a marked decrease in the cervical and uterine size. Resumption of cyclical ovarian activity occurred within a month in 7 animals. Five of these cows had 2 ovulations and two animals had 1 and 3 ovulations, respectively. A slight increase of the cervix and uterine size was observed in all ovulating animals in relation to the oestrous periods. Several different calculation methods of the ultrasonographic results were evaluated to describe the completion of uterine involution and compared with findings at rectal palpation. The best congruency with rectal palpation was found to use a 0.5 cm difference for comparison of the previous pregnant and non-pregnant uterine horns in singleton cows and an 80% reduction of the uterine size in all studied animals.