Deer, like all mammals, feed their young with milk, a process made possible by specialized structures known as teats. The straightforward answer to how many teats a female deer, or doe, possesses is four. This number is standard across most common species, including the white-tailed deer and mule deer. These structures are technically referred to as teats, which is the term used for the projection from the mammary gland in ungulates, rather than the smaller, less specialized nipple found in other mammals.
Number and Location
The four teats on a doe are arranged in two distinct pairs, which are positioned in the inguinal region between the hind legs. This location is similar to the udder of a cow, though significantly smaller and less conspicuous. A deer’s udder is often difficult to observe unless the doe is actively lactating.
In a non-lactating doe, the teats appear as small, subtle projections, often hidden beneath the fur of the lower abdomen. When the doe is nursing fawns, the mammary tissue swells with milk production, causing the entire udder to become more prominent and easily visible. Each of the four teats functions independently, drawing from its own separate mammary gland to supply milk to the young.
Purpose in Lactation
The primary function of the teats is to provide nutrition to the fawns following birth. The number of teats is generally related to the average litter size; since deer commonly give birth to one or two fawns, four teats provide redundancy and capacity for twins or triplets. Deer milk is highly nutritious, with a high fat and protein content that supports the rapid growth required for a fawn’s survival.
Research on red deer has shown that the four teats may not be identical in function, with differences observed along the longitudinal axis. For instance, the front teats, which are often the favored suckling position for fawns, sometimes produce milk with a slightly higher protein-to-fat ratio. If a teat is not suckled regularly, the body will stop producing milk in that specific quarter, eventually causing the gland to dry up.
Variation by Sex and Species
The presence of four teats is limited to the female deer, though male deer, or bucks, also possess rudimentary nipples. These nipples are non-functional remnants of embryonic development and are generally small, serving no purpose in milk production.
While four is the typical number for most deer species in North America, there is slight variation among the Cervidae family. The caribou, a closely related cervid species, may be an exception to the rule, sometimes having only two teats instead of four. However, the standard four-teat configuration is maintained across the vast majority of deer worldwide, including red deer, elk, and the common white-tailed and mule deer.