It is common for a cow that has difficulty in calving to bruise her uterus. The inflamed, swollen uterus quite often causes straining with prolapse of the vagina, cervix, or uterus. If prolapse does not occur, the placenta may be retained due to bruising inflammation. A thin, weak cow may have a prolonged calving process that commonly causes a bruised uterus. The incidence of retained placenta will increase if induced calving is utilized. Retained placenta may also be caused by a selenium deficiency. Consult your local Cooperative Extension agent to determine if your area is deficient in selenium. Selenium deficiencies are normally corrected by increasing the selenium content in a free-choice mineral or by injection. Work with a beef nutritionist before adding selenium to the mineral mix or feed. Excess selenium can be toxic to cattle.