Evaluation of uterine involution using radio-opaque markers during the postpartum period in Makuii ewes

After completion of the third stage of parturition and expulsion of the placenta, the uterus started to involuting until it reaches to normal size. The rate of uterine involution after parturition was studied in 6 healthy Makuii ewes. During second month of pregnancy the genital tract was exteriorized through a posterior midline laparatomy under general anesthesia and then four non-toxic split shots with different sizes were sutured on the serosal wall of the uterine body and horns. After parturition, the distance between markers was measured by sequential radiography. The mean length of the uterine body declined until 28 days after lambing but statistically maximum reduction was seen at about 14 days after parturition (P<0.05). Also, the mean diameter of gravid and non-gravid horn rapidly declined until 14 days postpartum (P<0.05) but reduction countinued until 42 days postpartum (P>0.05). The difference between the mean diameter of the gravid and non-gravid horn was not significant between days 14-42 (because of relatively small reduction in size). There were a high correlation between the measurements taken at the time of laparatomy and determined by radiography (4 days after surgery) for the mean length of uterine body (r = 0.89), the mean gravid horn diameter (r = 0.91) and non-gravid horn diameter (r = 0.79). In conclusion, after final statistical analysis of sequential radiographic views by using a repeated measurement analysis of variance, involution of the uterus in Makuii ewes was completed about 28 days postpartum for the uterine body and about 14 days for both the gravid and non-gravid horn. Radio-opaque marker is a useful method to study changes of the uterine size after parturition in live ewes.