Bulls have teats but not udders. Every bull is born with small, rudimentary teats, typically four of them, located on the underside of the belly in roughly the same spot where a cow carries her udder. But the udder itself, the large glandular organ that produces and stores milk, is absent in bulls. The confusion between these two structures is common, partly because people use the words interchangeably when they are actually describing different things.
What an Udder Actually Is
An udder is not just a bag with teats sticking out of it. It is a complex mammary organ made up of four separate glandular quarters, each with its own blood supply, milk-producing tissue, and internal duct system. In a lactating dairy cow, the udder can weigh over 50 kilograms when full of milk. It develops substantially during a heifer’s first pregnancy, under the influence of hormones like estrogen, progesterone, and prolactin. Without those hormonal signals in the right concentrations and sequence, the glandular tissue simply does not grow.
Teats, on the other hand, are just the external projections at the bottom of the udder. They serve as the delivery system: milk collects inside the udder and exits through a narrow canal inside each teat. In a cow, the teats are large, elongated, and functional. In a bull, the teats are small nubs with no functional glandular tissue behind them. They are there, but they are not connected to anything that produces milk.
So when someone asks whether bulls have udders or teats, the short answer is: teats yes, udder no. A bull’s teats are vestigial structures left over from early embryonic development, before the animal’s sex-specific anatomy fully took shape.
Why Bulls Have Teats at All
The reason bulls carry these small, seemingly pointless teats comes down to how mammalian embryos develop. In the earliest stages of development, bovine embryos follow a shared anatomical blueprint regardless of sex. Teat buds begin forming before the hormonal signals that drive male or female development have fully kicked in. By the time testosterone starts masculinizing a male calf’s body, the teat structures are already in place. Rather than being actively removed, they simply stop developing further.
This pattern holds across nearly all mammals. Most male mammals possess nipples or teats, and losing them during fetal development is actually the rare exception rather than the rule. A few rodent species, like mice and rats, do lose their nipples before birth through a specific hormonal mechanism, but in the vast majority of mammals, including cattle, the male retains these structures throughout life.1PubMed Central. Developmental basis of male nipple loss and retention in mammals In most species, the androgen receptor appears to be inactive in the developing mammary region, so testosterone does not trigger the destruction of the teat bud the way it does in those few rodent species.
The result is that a bull calf is born with four small teats in the inguinal region. They serve no function in the male, but they are not harmful either, so there has been no strong evolutionary pressure to eliminate them. They are, in essence, a harmless leftover from a developmental plan that is shared between the sexes.
What Bull Teats Look Like
If you have only ever seen the prominent teats on a dairy cow, a bull’s teats might surprise you. They are small, often just a centimeter or two long, and sit flat against the belly skin. On a mature bull with a thick hide and heavy musculature, they can be difficult to spot unless you are specifically looking for them. They are located in the same general area as a cow’s udder, between the hind legs, but without the surrounding mass of glandular tissue they do not protrude in any obvious way.
In young bull calves, the teats are often more noticeable relative to body size. As the bull matures and puts on muscle and fat in the surrounding area, the teats become even less conspicuous. Some breeds carry slightly more prominent vestigial teats than others, but there is no breed where a bull’s teats approach anything close to the size or functionality of a cow’s.
Ranchers and farmers generally ignore bull teats entirely. They require no maintenance, cause no health problems, and play no role in breeding evaluations or performance assessments. The teats are just quietly there, doing nothing.
Can Male Cattle Ever Develop Udder-Like Tissue?
Under normal circumstances, no. But there are documented cases where male cattle, particularly steers (castrated males), have developed noticeable mammary gland tissue. The most well-studied trigger is exposure to phytoestrogens, which are plant-derived compounds that mimic the effects of estrogen in the body.
Certain forage plants, especially some varieties of clover and alfalfa, produce compounds like coumestrol and isoflavones in concentrations high enough to affect livestock. When steers graze on pastures with high coumestrol levels, at concentrations above roughly 37 milligrams per kilogram of dry matter, anecdotal and clinical reports describe the development of mammary tissue, a condition called gynecomastia.2PubMed Central. Phytoestrogens: A Review of Their Impacts on Reproductive Physiology and Other Effects upon Grazing Livestock Steers are more susceptible than intact bulls because castration removes the testosterone that would otherwise counterbalance estrogen-like effects.
Similar phenomena have been observed in other livestock. In sheep, wethers (castrated males) exposed to high levels of dietary phytoestrogens have developed mammary tissue and in some cases even begun lactating, despite being male and never having been pregnant.3PubMed Central. Isoflavones in Animals: Metabolism and Effects in Livestock and Occurrence in Feed These cases demonstrate that the genetic machinery for mammary development exists in males; it just normally stays switched off in the absence of the right hormonal signals. When phytoestrogens flood the system, that switch can get flipped.
For intact bulls with normal testosterone levels, gynecomastia is extremely rare. The hormonal environment of an intact bull strongly suppresses any mammary tissue development, even in the presence of moderate phytoestrogen exposure. But the steers-on-clover cases are a fascinating reminder that the difference between a functional udder and a vestigial teat is largely hormonal, not strictly genetic.
Bulls, Steers, and Oxen
Part of the confusion around this question comes from the fact that people often use “bull” loosely to refer to any male bovine, when cattle terminology actually distinguishes several categories. A bull is an intact (uncastrated) adult male. A steer is a castrated male, typically castrated young for meat production. An ox is a castrated male trained for draft work. A calf is any young animal regardless of sex, though bull calf and heifer calf specify which.
The distinction matters here because castration status affects what happens with those vestigial teats. A bull’s high testosterone levels keep mammary tissue firmly suppressed. A steer, lacking that testosterone, is slightly more susceptible to estrogenic influences, whether from dietary sources like phytoestrogens or from other environmental exposures. In practical terms, the overwhelming majority of steers never develop anything resembling an udder either, but the rare cases of mammary development in male cattle are almost always in steers, not bulls.
All three categories of male cattle, bulls, steers, and oxen, have the same four vestigial teats. Castration does not cause the teats to grow or change. It simply alters the hormonal environment in ways that, under unusual dietary conditions, could theoretically allow some mammary tissue to respond to estrogen-like compounds.
Extra Teats in Cattle
A separate but related phenomenon worth knowing about is supernumerary teats, meaning extra teats beyond the normal four. This occurs in both male and female cattle, though it draws the most attention in dairy cows because extra teats can interfere with milking equipment or become sites of infection.
Supernumerary teats are surprisingly common in cattle. Estimates of their prevalence vary across breeds and herds, but it is not unusual for a significant percentage of animals in a herd to carry one or two extra teats. These extras can appear anywhere along the “milk line,” the embryonic ridge where mammary tissue has the potential to develop. In females, extra teats sometimes connect to functional glandular tissue, but more often they are blind, meaning they have no duct leading to a milk-producing quarter.
In bulls, extra teats are simply extra vestigial nubs. They are neither more nor less functional than the standard four. Breeders sometimes pay attention to supernumerary teats in bulls used for dairy breeding because the trait can be passed to female offspring, where it becomes a practical nuisance. A dairy bull that consistently sires daughters with extra teats may be selected against, even though the extra teats themselves cause no problem in the bull.
The genetics of supernumerary teats are not fully pinned down. The trait does not follow a simple one-gene inheritance pattern. Multiple genes appear to be involved, along with possible developmental variation. It is one of those traits that breeders track and manage without having a complete genetic map to work from.
How to Tell a Bull from a Cow at a Glance
For people who are not around cattle regularly, telling bulls from cows in a field can be less obvious than it sounds, especially at a distance. The udder is actually one of the most reliable visual cues. A lactating dairy cow carries a large, visible udder between her hind legs. A beef cow’s udder may be smaller but is still evident, particularly when she is nursing a calf. A bull, with no udder and only tiny vestigial teats hidden against his belly, looks distinctly different from behind.
Other differences help too. Bulls tend to be larger and more heavily muscled, especially through the neck, shoulders, and chest. They often carry a more pronounced crest of muscle along the top of the neck. Their heads are broader and blockier. But these differences are breed-dependent and can be subtle in younger animals. A yearling bull and a yearling heifer of the same breed can look quite similar from a distance, and neither will have a prominent udder at that age.
The behavioral cues are often more telling than anatomy. A bull in a pasture with cows will typically be patrolling, checking cows for signs of heat, and carrying himself with a distinctive posture. But if you are just driving past a field and want a quick answer, look underneath: a big, swinging bag between the hind legs means cow. Nothing visible means bull, steer, or a heifer that has not yet calved.
Male Nipples Across Livestock Species
Cattle are far from unique in this arrangement. Male horses have small teats on the sheath area. Male goats have two teats that are often more visible than a bull’s because goats carry less body mass to obscure them. Male sheep similarly retain vestigial teats. In pigs, boars have a row of small nipples along the belly, just as sows do, though the boar’s nipples remain flat and nonfunctional.
The consistency across species reinforces the developmental explanation. The mammalian body plan includes nipple or teat structures as standard equipment, laid down before sex-specific development diverges. The few mammalian species where males lose their nipples entirely, like mice and rats, are the ones that need a special explanation, not the species where males keep them.1PubMed Central. Developmental basis of male nipple loss and retention in mammals
For livestock producers, male teats and nipples are a non-issue in daily management. They do not affect fertility, growth rate, carcass quality, or any other production trait. The only context where male teat anatomy matters at all is in dairy breeding programs, where a bull’s teat conformation, including the number, placement, and shape of his vestigial teats, can serve as a rough predictor of what his daughters’ teats will look like. Dairy bull studs will sometimes photograph and score a bull’s rudimentary teats as part of a broader conformation evaluation, knowing that teat traits have some heritability. A bull with well-placed, evenly spaced vestigial teats is considered slightly preferable to one with oddly positioned or extra teats, simply because those traits may show up in more exaggerated form in his milking daughters.
Outside of that niche breeding context, a bull’s teats are one of those anatomical details that most people never notice and never need to think about. They are real, they are normal, and they are completely harmless remnants of a shared developmental starting point.