What are the signs and indications that a sow is about to farrow?

As the time of farrowing approaches, a sow about to give birth shows different signs. Accurately determining when a sow will farrow helps with preparing for and assisting at the birth, and improves piglet survival rates. The average gestation period of a sow is 114 days, though it may be earlier or later depending on the individual, so after a sow enters the farrowing pen, you should constantly watch for signs that farrowing is imminent.

From 3 to 5 days before farrowing, the sow's vulva becomes red, swollen and relaxed, taking on a purplish-red color, with mucus discharge, and the areas on both sides of the tail base sink in; the udder swells, becomes shiny and red (especially obvious in first-time sows), the teats on both sides become thick and long, clearly protruding in a splayed shape, and one or two days before farrowing, milk can be squeezed from the front teats, and when thick milk can be squeezed from the last pair of teats, the sow will farrow in about two hours.

From 6 to 12 hours before farrowing, the sow often picks up straw to build a nest; when there is no straw to pick up, she will root at the ground with her snout and paw at the ground with her front hooves as if building a nest; the sow is tense and restless, lying down and getting up from time to time, suddenly stops eating, and frequently passes dung and urine in small, short, soft amounts; when thin, blood-tinged mucus flows from the vulva, it means the sow's “water has broken” and she will give birth in about half an hour. In practice, a sow picking up straw to build a nest and thick milk being squeezed from the last pair of teats and shooting out in a jet are often used as the main signs for judging that a sow is about to farrow.