Teats

Teats are the outlets of the mammary gland through which milk is secreted in female mammals and, in some species, in males. They are essential for lactation, providing a route for milk transfer to offspring during nursing. The appearance, size and number of teats vary widely among species.

Anatomically, a teat consists of an external opening at the tip—the teat canal or streak canal—surrounded by a teat base. Inside, milk collected from milk-producing glands is carried through ducts to the gland cistern and then to the teat cistern and surface for release. The teat canal is protected by a sphincter muscle to limit contamination. Milk production occurs in alveolar tissue, driven by hormonal signals, and milk is ejected by the action of smooth muscle and oxytocin.

Species variation is large. The number and arrangement of teats differ widely: cattle commonly have four teats, horses typically have two, small ruminants such as sheep and goats usually have two, and pigs may have many teats along the abdomen. Teat development occurs before birth in many species, and lactation follows parturition, with colostrum produced initially to provide immunity to the newborn. Milk ejection relies on coordinated hormonal responses and mechanical removal via nursing or milking.

Health and management concerns include teat injuries and infections, notably mastitis, which can affect milk quality and animal welfare. Good milking hygiene, proper technique, and regular inspection help prevent problems. In humans, the term teat is less commonly used; it is more often applied to animal anatomy, while humans refer to nipples when describing the corresponding structure.