Ultrasonic observation of postpartum uterine involution in the cow.

To learn about the progress of postpartum uterine involution in the dairy cow, the authors wanted to know whether the ultrasonic linear scanner is applicable for this purpose. The uterus was observed by the transducer, which was inserted into the rectum. Clear cross-sectional images of the endometrium were obtained in this way; however, those of the myometrium and the perimetrium were not very clear. Observation on the progress of uterine involution was started on Day 8 postpartum and continued to Day 43 postpartum. The diameter and area of the uterine horn and the endometrium in cross-sectional ultrasonograph images of the endometrium were estimated using a Magiscan 2 image analyzer. The relationship between the estimated dimensions of the uterine horn and postpartum days were satisfactorily fitted into polynomial regressions. Using the ultrasonic linear scanner, it was confirmed that uterine involution was completed at approximately 40 d postpartum. The applicability of the ultrasonic linear scanner for diagnosis of uterine involution in the postpartum cow is demonstrated by the results of the present study.