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Teat
Teat
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Teats protruding from the udder of a cow
Part of a milking device that fits over the teats of a cow.

A teat is the projection from the mammary glands of mammals from which milk flows or is ejected for the purpose of feeding young.[1][2][3] In many mammals, the teat projects from the udder. The number of teats varies by mammalian species and often corresponds to the average litter size for that animal.[4][5] In some cases, the teats of female animals are milked for the purpose of human consumption.

The quality of some domesticated animals is determined by the establishment of desired characteristics, such as teat size and placement.[6][7]

Number and positioning in other animals

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The number and positioning of mammary glands and teats varies widely among mammals. The protruding teats and accompanying glands can be located anywhere along the two milk lines. In general, most mammals develop mammary glands in pairs along these lines, with a number approximating the number of young typically birthed at a time. The number of teats varies from 2 (in elephants and anthropoids) to 18 (in pigs). Marsupials usually have 4 to 12 teats,[8] but the Virginia opossum has 13, one of the few mammals with an odd number.[9][10] The following table lists the number and position of teats and glands found in a range of mammals:

Species[11] Cranial teats
(thoracic)
Intermediate teats
(abdominal)
Caudal teats
(inguinal)
Total teats
Goat, sheep, horse
guinea pig
0 0 2 2
Polar bear 4 0 0 4
American black bear, Asian black bear, grizzly bear 4 0 2 6
Camel 0 0 4 4
Cattle 0 0 4 4
Cat 2 2 4 8
Dog 4 2 2 or 4 8 or 10
Mouse 6 0 4 10
Rat 6 2 4 12
Pig 4 4 4 12
Elephants, Anteaters, anthropoids (including humans) 2 0 0 2

Disease of teats

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A number of diseases can affect the teats of cattle.[12]

Goats are also affected by diseases of the teats.[13]

Etymology

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Teat is derived from the Old French or Dutch word, "tete" or the Greek word τιτθύς.[14] An alternative, but possibly not unrelated, would be the Welsh word "teth" or the Old English, "titt" which is still used as a slang term. The words "teat" and "tit" share a Germanic ancestor. The second of the two, tit, was inherited directly from Proto-Germanic, while the first entered English via Old French.[15][16]

See also

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References

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Revisions and contributorsEdit on WikipediaRead on Wikipedia
from Grokipedia
A teat is the protruding structure of the in female mammals, through which is discharged from ducts to nourish offspring during . It consists of a for storage, a narrow lined with acting as a barrier against , and an external opening () regulated by a muscle. The mammary glands, including teats, are a defining characteristic of mammals (class Mammalia), evolving as modified sweat glands to provide nutritional and immunological support to young via secretion stimulated by hormones like and oxytocin. In most eutherian mammals, multiple teats are arranged in pairs along the ventral body, varying in number from two (e.g., humans, ) to over a dozen (e.g., some with up to 12); marsupials often have teats within a pouch for securing joeys during suckling. Monotremes like platypuses lack true teats, instead secreting from glandular patches. Teats play a critical role in , with their influencing milk flow rates and susceptibility to conditions like in species such as cows, where each of the four teats corresponds to a separate mammary quarter. In domestic animals, teat morphology affects milking efficiency and , while in wild mammals, adaptations like the small, thumb-sized teats in whales facilitate underwater .

Definition and Overview

Biological Definition

A teat is defined as the protruding projection from the of therian mammals (marsupials and placentals), through which is ejected to nourish during suckling. This structure serves as the primary outlet for , enabling the transfer of nutrients, antibodies, and hydration essential for neonatal . In mammals possessing multiple mammary glands, such as ruminants, the teats function as individual outlets within the udder, a pendulous organ that encompasses two or more glands, each terminating in a separate teat for milk discharge. The evolutionary development of teats arose alongside mammary glands in the synapsid ancestors of mammals over 200 million years ago, adapting from apocrine-like cutaneous glands to support viviparous reproduction by providing post-birth nourishment that enhanced offspring viability and enabled the diversification of mammalian lineages. This underscores lactation's role in mammalian evolutionary success. The mammary glands, as the encompassing glandular system unique to the class Mammalia, produce the delivered via teats. The term "teat" is primarily employed in reference to the mammary projections of non-human mammals, especially quadrupeds such as and , whereas "" is the standard designation for the analogous structure in humans and certain . This terminological distinction arises from contextual conventions in veterinary and medical fields, where "teat" emphasizes the functional protrusion from an or mammary mass in animals adapted for . Structurally, teats in many mammals are elongated and pendulous, often extending downward to enable suckling by positioned ventrally beneath the , in contrast to the shorter, more erect nipples of humans that project from the chest for direct, face-to-face . For instance, in cows, the teats form part of the pendulous containing multiple milk ducts, while human nipples are compact protrusions atop individual glands. In veterinary literature, "teat" is the conventional term for domesticated species—such as the four teats on a bovine or the paired teats on a caprine —highlighting their role in milk delivery, whereas human medical contexts favor "" to describe the same basic structure, with occasional interchangeable usage across disciplines for clarity. This reflects broader adaptations in positioning along the body axis, from abdominal in quadrupeds to thoracic in bipeds.

Anatomy and Development

Structural Components

The teat is a protruding, cylindrical structure covered by skin, extending from the mammary gland in mammals and serving as the conduit for milk ejection. Its external surface features sensory nerve endings sensitive to touch and pressure, facilitating interactions during nursing. The distal end terminates in the teat orifice, a small external opening that connects directly to the internal teat canal. The teat canal (known as the streak canal in ruminants), also referred to as the ductus papillaris in some contexts, is a narrow, keratin-lined passageway varying in length across species (approximately 1-2 cm in ruminants), acting as a primary barrier against bacterial ingress due to its stratified squamous epithelium and accumulated keratin plug. In ruminants, the proximal junction of the teat canal with the teat cistern features Furstenberg's rosette, comprising 6-10 longitudinal mucosal folds that trap pathogens and contribute to local immune defense mechanisms. In humans and some other mammals, the features multiple (typically 15-20) lactiferous ducts converging to openings on the surface, differing from the single in many quadrupeds. Internally, the is reinforced by , including collagenous stroma that provides structural support and elasticity, varying in composition from fibrous to adipose-rich matrices across species. Bundles of fibers, oriented both longitudinally and circularly around the teat and teat wall, enable active contraction to close the orifice and prevent leakage between sessions. A extensive vascular network supplies the and connects it to the alveolar structures of the for nutrient exchange and oxygenation, with arterial supply varying by species (e.g., external pudendal in ruminants, internal thoracic in humans). Teat size and texture exhibit interspecies variations, influenced by factors such as the density of and the overall stromal architecture, which adapt to differing configurations and reproductive demands.

Embryological Origins

The embryological development of teats in mammals originates from paired milk lines, which are ridges of thickened that form along the ventral surface of the during early embryonic development, such as approximately weeks 4 to 6 in . These milk lines, also known as mammary ridges, extend bilaterally from the axillary to the inguinal area and represent the initial site of mammary primordia formation across mammalian . The developmental process begins as the milk lines segment into a series of mammary placodes, or buds, through localized ectodermal proliferation and mesenchymal . In most mammals, multiple buds initially form along each ridge, but only specific ones persist to develop into functional teats, while the majority undergo programmed regression via , ensuring species-appropriate positioning and number. This selective development establishes the teat as the external outlet connected to the underlying . Hormonal influences during fetal development contribute to in teat formation, with and progesterone playing key roles in modulating epithelial growth and mesenchymal interactions. In female fetuses, these ovarian hormones promote the progression of mammary buds into more elaborate structures, whereas in males, the presence of androgens leads to inhibition and regression, resulting in rudimentary teats that remain nonfunctional postnatally. This dimorphism is further supported by signaling pathways, such as (PTHrP), which is essential for maintaining bud integrity in females while allowing regression in males.

Physiological Role

In Lactation and Nursing

In mammals, teats serve as essential conduits for during , channeling synthesized in the mammary alveoli through the ductal to the and ultimately to via the teat canal. Milk production occurs in the epithelial cells of the alveoli, where it is secreted into alveolar lumens and gradually moves to the larger for temporary storage, with teats facilitating this flow while maintaining structural integrity to support efficient ejection. The let-down , critical for milk release, is regulated by oxytocin, which contracts myoepithelial cells surrounding the alveoli and ducts, propelling toward the teats. During , suckling by the offspring stimulates mechanoreceptors and endings in the teat's and streak , sending afferent signals to the and triggering oxytocin release from the . This hormonal surge induces the milk ejection reflex, causing coordinated contractions that force from the alveoli into the and relax the teat muscle, allowing unimpeded flow through the teat . The teat , a ring of at the canal's base, normally remains contracted to seal the duct but relaxes under oxytocin influence during let-down, ensuring is available only on demand. Hormonal control of lactation involves , secreted by the in response to suckling stimuli, which promotes milk synthesis by stimulating alveolar epithelial cells to produce and secrete milk components like , proteins, and fats. levels remain elevated with frequent , sustaining ongoing synthesis, while the teat's and the streak canal—a narrow, keratin-lined passage—prevent passive leakage of cisternal between feedings, preserving udder pressure and availability for the young. This dual regulation ensures teats function as both outlets and barriers in the natural process.

Milking in Domesticated Animals

In domesticated animals such as cows, , and sheep, milking serves as a key agricultural practice for extracting intended for consumption, distinct from natural behaviors. Manual milking, often referred to as hand-stripping, involves gently squeezing the base of the teat and stripping downward to express into a collection vessel, typically used in small-scale operations with fewer than 15 animals. This technique requires clean, dry hands and a "strip, dip, and wipe" procedure—stripping the first few streams of into a separate to check for abnormalities, dipping the teat in a sanitizing solution like iodine, and wiping with a disposable —to maintain and stimulate the lactation reflex. For larger herds, machine predominates, utilizing portable bucket milkers or systems where is drawn through tubes to a central for cooling. These methods are adaptable across , with adjustments for teat size in and sheep, which often require smaller teat cups compared to those for cows. Machine milking systems replicate the natural suckling process through a combination of and pulsation mechanisms to ensure efficient and gentle extraction. A creates suction within teat cups, which consist of a rigid shell enclosing a flexible rubber or liner that collapses and expands around the teat; this alternates between applying to draw and releasing to , mimicking the intermittent movements of a suckling calf, kid, or lamb. The pulsator controls this rhythm, operating at approximately 60 pulses per minute for cows, 90 for goats, and 120 for sheep to match species-specific and prevent tissue congestion. Proper attachment within 60-90 seconds after teat preparation optimizes let-down, while automated detachment sensors in modern systems halt when flow ceases, reducing manual intervention. These designs, refined over decades, facilitate twice-daily routines that align with cycles of 100 days in sheep and up to 305 days in cows and goats. Regarding , practices must balance efficiency with minimizing stress and to teats, as improper techniques can lead to damage and compromised tissue integrity. Over-—continuing extraction after the udder is empty—exposes the teat to prolonged vacuum, causing (thickened, rough teat ends) and increasing susceptibility to bacterial entry, which heightens risks and discomfort during subsequent milkings. In and sheep, smaller teats are particularly vulnerable to bruising from ill-fitting liners or excessive pulsation, potentially leading to reluctance to enter milking parlors and reduced overall mobility. Modern advancements, such as softer liners and variable pulsation rates, promote better blood flow and reduce , enhancing comfort; for instance, attaching cups promptly after supports the natural let-down without undue pressure. Welfare-focused protocols, including pre- and post-dipping, further protect teat skin and support voluntary participation in automated systems. The economic significance of teat health in milking operations cannot be overstated, as it directly influences yield and quality across . In dairy cows, subclinical teat issues from poor practices can reduce yield by 4-10% at somatic cell counts exceeding 250,000 per ml, escalating to 18% losses at higher levels, with associated costs of €150-500 per case including discarded and treatments. For goats and sheep, maintaining intact teats ensures consistent production—up to 1-2 liters daily per and 0.5-1 liter per ewe—while damage leads to elevated counts above 1,000,000 per ml, disqualifying from premium markets and prompting . Overall, robust and equipment calibration can improve farm profitability through higher yields and fewer veterinary interventions, underscoring the value of welfare-integrated practices in sustainable production.

Variations Across Mammals

Number and Positioning

The number of teats in mammals varies widely, typically ranging from 2 to 13 or more, often correlating with the ' average litter size to support multiple offspring during nursing. For instance, with small litters, such as and , possess 2 teats, sufficient for a single young, whereas -bearing like pigs have 12-14 teats to accommodate larger broods of 8-12 piglets. This numerical variation reflects adaptations to reproductive strategies, where the number of functional teats ensures adequate distribution without excess. Teats develop along paired embryonic milk lines that extend bilaterally from the thoracic region to the inguinal area, resulting in symmetrical positioning. These lines give rise to glands in three primary locations: thoracic (on the chest, as in ), abdominal (along the belly, common in carnivores and ), or inguinal (in the , typical of ungulates). The milk lines originate from ectodermal thickenings during early embryogenesis, allowing potential development at multiple sites along their length. This arrangement retains an evolutionary trace of an ancestral multi-teat configuration in synapsids, where glands localized progressively along the lines for efficiency. The following table illustrates representative examples of teat number and positioning across mammal species:
SpeciesNumber of TeatsPosition
Primates (e.g., humans)2Thoracic
Elephants2Thoracic
Horses2Inguinal
Dogs8-10Abdominal
Pigs12-14Abdominal
Opossums13Abdominal

Species-Specific Adaptations

Teat morphology in mammals exhibits evolutionary adaptations that align with species-specific lifestyles and reproductive strategies, particularly in facilitating efficient under diverse ecological constraints. In polytocous species, such as many , which produce large , the presence of multiple teats—often numbering 8 to 12 or more—enables simultaneous of numerous , thereby maximizing survival rates in high-fecundity reproductive systems. This correlation between teat number and litter size is a longstanding observation, where the average litter size approximates half the number of teats, and the maximum litter size rarely exceeds the total teat count, reflecting an evolutionary constraint that prevents overcommitment of maternal resources. Conversely, in monotocous like whales, which typically birth a single calf, only two teats are present, streamlined for focused in an aquatic environment where occurs underwater and calves must quickly learn to surface for air. Unique adaptations appear in basal mammals, such as monotremes (egg-laying species including the and echidnas), which lack true teats altogether; instead, mammary glands secrete milk directly through specialized skin pores or patches on the , from which hatchlings lap the fluid. This "pseudo-teat" mechanism represents a primitive evolutionary stage in , predating the development of nipples in therian mammals (marsupials and placentals), and suits the monotremes' reptilian-like reproductive mode while still providing essential nourishment. In volant mammals like bats, teat structure supports amid an aerial lifestyle, with females typically possessing one or two pairs of pectoral to which pups firmly attach, often remaining latched during the mother's inverted roosting or short flights. This secure attachment via specialized morphology ensures pup transport and feeding without detachment, an critical for where mothers nocturnally and leave roosts frequently.

Health Issues and Management

Common Diseases

Mastitis represents one of the most prevalent diseases affecting teats in mammals, particularly and , characterized by of the often originating from bacterial invasion through the teat canal. Common pathogens include and various species, leading to symptoms such as teat swelling, pain, heat, and abnormal milk appearance including clots or discoloration. In , subclinical predominates, affecting up to 50% of quarters in some herds, while clinical cases involve visible and reduced milk yield; in , the disease similarly causes udder firmness and milk contamination, with spp. as primary isolates. The highlights contagious transmission during and environmental exposure, with higher incidence in high-producing herds. Teat , or bovine papillomatosis, are viral lesions caused by types 1, 2, or 6, manifesting as benign, frond-like growths on the teat skin that can interfere with and predispose to secondary infections. These warts typically appear in young animals, spreading through direct contact or contaminated environments, and may resolve spontaneously but often persist for months, causing discomfort and economic losses from hide damage. Hyperkeratosis involves abnormal thickening of the layer at the teat orifice, resulting from chronic and commonly observed in dairy cows subjected to mechanical milking. It presents as rough, elongated teat ends that increase susceptibility to by impairing canal closure, with prevalence linked to teat shape—such as tapered or pointed teats—and milking frequency. Teat , a blockage of the teat orifice due to from chronic irritation such as horn fly , occurs sporadically in , preventing flow from the affected quarter and requiring intervention to support by neonates. This condition is associated with environmental factors like exposure to horn fly irritation in affected herds. Key risk factors for these teat diseases include poor hygiene during milking, which facilitates bacterial entry via the streak canal, and physical trauma from aggressive suckling, rough handling, or malfunctioning milking equipment. In , similar vulnerabilities stem from environmental contamination and , exacerbating rates.

Preventive and Treatment Measures

Preventive measures for teat health in emphasize protocols to minimize bacterial entry during . Post-milking teat dips, typically containing iodophors or , are applied to disinfect the teat end and form a protective barrier against pathogens, reducing new intramammary infections by up to 50% according to National Council guidelines. Premilking involves forestripping and teats with and a mild to remove dirt and before attachment of milking units. Maintaining clean and alleyways further limits environmental contamination of teat ends. Selective breeding programs target teat morphology traits, such as teat length, diameter, and placement, to enhance resistance to injuries and infections. In , genetic evaluations incorporate linear scoring of udder conformation, where favorable teat traits like shorter, cylindrical teats are prioritized to improve milking efficiency and reduce . Breeding indices from organizations like ABS Global include teat scores to select sires that produce daughters with robust teat structures, correlating with lower counts. Nutritional strategies support teat health by bolstering immunity through supplementation of trace minerals and vitamins. and enhance function, reducing susceptibility to teat canal infections, with studies showing decreased incidence in supplemented herds. and are critical for epithelial integrity and defense in teat tissues, as outlined in veterinary guidelines for cows. Treatment of teat infections primarily involves targeted antimicrobial therapy to address clinical signs such as swelling or discharge. Intramammary antibiotics like cephapirin or pirlimycin are infused directly into affected during lactation, following withdrawal periods to ensure milk safety, as recommended by the . For dry cows, selective dry cow therapy uses antibiotics only in infected , combined with internal teat sealants to physically block ascent. Topical antiseptics, including silver-based dips, are applied to superficial teat lesions to promote healing and prevent secondary infections. Surgical interventions correct structural defects, such as supernumerary teats, through excision using staples under , typically performed on dry cows to avoid milking interference. For severe teat injuries like lacerations, and suturing may be required, with postoperative coverage to mitigate infection risk, per dairy surgery protocols. Monitoring teat health relies on standardized scoring systems and for early detection of abnormalities. The California Mastitis Test-adapted teat scoring evaluates and smoothness on a 0-3 scale, performed routinely in parlors to identify at-risk teats before onset. imaging assesses teat canal integrity and plug formation during the dry period, enabling non-invasive detection of subclinical issues in veterinary diagnostics. Digital platforms enhance scoring consistency by analyzing teat images for automated condition assessment.

Etymology and Terminology

Historical Origins

The word "teat" entered around the as "tete," borrowed directly from "tete" (modern French "tette"), denoting a or . This term originated from Frankish *tittā or *tittō, a form derived from Proto-Germanic *tittaz, meaning "teat" or "." The Proto-Germanic root *tittaz is cognate with "tit," an early term for the female or , reflecting a shared Germanic linguistic heritage focused on suckling and nourishment. It is of expressive origin, likely imitating the sound of sucking. Similarly, Egyptian iconography portrayed the goddess Hathor as a cow with prominent udders, symbolizing maternal milk flow and celestial fertility tied to the Milky Way. Historically, "teat" functioned interchangeably as a synonym for "nipple" in medieval English texts, often referring to human anatomy in medical and literary descriptions of infancy and lactation. By the 18th century, as veterinary science formalized in Europe, the term shifted toward animal-specific usage in treatises on husbandry and dairy production, distinguishing bovine or ovine teats from human equivalents to address practical concerns like milking and mastitis. In contemporary contexts, this evolution underscores "teat" as primarily an animal descriptor, separate from human "nipple."

Modern Usage and Synonyms

In contemporary scientific and agricultural terminology, "teat" serves as the primary term for the nipple-like projection of the mammary gland in mammals, particularly in veterinary and dairy contexts. Informal synonyms in farming include "dug," which refers to the teat or udder, especially when emphasizing suckling in livestock. Archaic or dialectal English variants such as "pap" denote the nipple or teat, retaining usage in regional or literary expressions. Regional variations in English highlight differences in preference: in British English, "tit" is employed regionally for small teats or nipples, often in informal or dialectal speech, while American English consistently favors "teat" for anatomical and practical descriptions across contexts. In veterinary science, "teat" is integral to specialized procedures like teat endoscopy (theloscopy), a minimally invasive technique used to diagnose and treat milk flow obstructions in dairy cattle by visualizing the teat canal. Within the dairy industry, the term features prominently in products such as internal teat sealants, non-antibiotic pastes like Orbeseal that form a physical barrier in the to prevent new intramammary infections during the dry cow period, reducing clinical risk by 29% when combined with antibiotics. These sealants are administered via intramammary and are standard in modern protocols. Culturally, references to the teat in frequently symbolize nurture and maternal sustenance, as evident in where imagery underscores bonds of care and tyranny in maternal figures. Such motifs appear in works exploring motherhood, adapting historical connotations to contemporary themes of provision and protection.

References

  1. https://en.wiktionary.org/wiki/teat
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