Many think that lactation in the mare is not that important, especially compared to the dairy cow, from which milk is taken directly for human consumption. However, the importance of lactation in the mare must not be underestimated. Indeed, some cultures do collect milk from mares for human consumption, but normally mare milk production is only indirectly evident in the growth and development of her foal. As such, it warrants consideration in some detail. An understanding of lactation is important to provide the best start in life for the foal.

Anatomy of the Mammary Gland

Milk is produced in the udder or mammary gland of all mammals (hence the term mammal). Different mammals have a differing number of mammary glands situated in pairs along the abdomen on either side of the midline. Some mammals, such as pigs, have up to 20 (10 pairs), whereas primates have only two. The mare has four mammary glands (two pairs) situated between the hind legs; they are protected by a layer of skin and hair that covers the whole surface of the glands. In the area of the teats, the skin is hairless and particularly sensitive in order to react to the foal’s suckling.

The mammary gland as a whole is supported by, and attached to, the body of the mare by sheets of ligaments (Figure 1). In most mammals, each gland has its own teat, so in the mare you would expect there to be four (like a cow). However, the mare is relatively unique in that each pair of glands on either side of the midline joins together and exits via a single teat, so the mare has only two teats (Figure 2)