udder

An udder is the external mammary gland of female mammals in many hoofed species, most notably cows, goats, and sheep. It is a paired organ that often contains multiple milk-producing quarters; each quarter has its own teat that releases milk through a separate opening. In cows the udder typically has four quarters (two left, two right), whereas goats and sheep usually have two quarters. The udder is suspended by ligaments and supportive tissue and is covered by skin and hair, with the teats projecting downward for milking.

Internally, each quarter contains glandular tissue capable of producing milk, connected to a system of ducts that drains into a cistern and teat canal. The milk is supplied by blood vessels and is regulated by hormones, especially prolactin for milk synthesis and oxytocin for milk ejection in response to teat stimulation or nursing.

Udder health is a key concern in dairy production. Mastitis, an inflammation often due to infection, is a leading welfare and economic issue and is diagnosed by signs such as heat, swelling, pain, abnormal milk, or reduced production. Prevention relies on good milking technique, sanitation, proper housing, and veterinary management, including dry-cow therapy and regular monitoring.

Other domestic species with udders or similar mammary systems include buffalo and camels, which also produce milk for human use. The study of udder anatomy and function informs dairy management, animal welfare, and breeding programs aimed at improving milk yield and udder conformation.