In sows, fetal membranes are usually expelled within 4 hours after farrowing, but the time can range from minutes to 12 hours. Retained placentae are often contained within the uterus and are not visible at the vulva. In this species, failure to expel fetal membranes indicates there are likely still piglets retained within the uterus as well.
Usually, the fetus or membranes decompose in situ. This may be accompanied by clinical signs of systemic illness and a purulent vaginal discharge.
Antimicrobial treatment is indicated in animals with systemic clinical signs of illness. Although serious or fatal sequelae occasionally occur, the prognosis for recovery and future fertility is good.