Sheep do have teeth, but not where most people expect them. The upper front of a sheep’s mouth has no incisors at all. Instead, the lower jaw carries a row of sharp, chisel-like incisors that press against a thick, rubbery pad of tissue on the upper jaw, forming a surprisingly effective tool for cropping grass close to the ground. Behind those front teeth, both upper and lower jaws are lined with molars and premolars used for grinding. The full set adds up to 32 permanent teeth in an adult sheep, and the condition of those teeth often determines how long a ewe stays productive in a flock.
What the Inside of a Sheep’s Mouth Actually Looks Like
If you pried open a sheep’s mouth and looked at the front, you would see eight incisors sitting in a neat arc across the lower jaw. Directly opposite them, on the upper jaw, sits the dental pad: a firm ridge of keratinized tissue roughly 1.6 inches wide that acts as a cutting board against which the lower incisors can shear grass blades.1Forage Information System. How does Grass Regrow? This setup evolved to let sheep exert a friction or “nip” force between the incisors and the pad, gripping and tearing forage rather than snipping it the way an animal with upper and lower incisors might.2New Zealand Journal of Agricultural Research. The tooth to pad relationship in sheep ‐ some mechanical considerations
Farther back, past a gap called the diastema (the toothless stretch between the incisors and the cheek teeth), each side of the jaw holds three premolars and three molars, top and bottom. These 24 cheek teeth are ridged and broad, built for the relentless side-to-side grinding that breaks plant fiber into digestible pulp. Sheep chew their cud for hours each day, and the forces involved in that rumination chewing are substantial, with longer loading cycles and sustained jaw strain compared to the initial cropping bites.
Why No Upper Front Teeth
The missing upper incisors are not a quirk unique to sheep. Cattle, goats, and deer share the same arrangement, which is a hallmark of ruminant herbivores. The dental pad is no accident of nature; it gives the animal a compliant, slightly yielding surface to press forage against, which is ideal for gripping slippery grass blades. A hard upper tooth row meeting a hard lower row would be good for slicing through a carrot, but less effective for pulling and tearing an uneven mouthful of wet pasture plants.
Sheep also have deeply cleft upper lips that spread apart to expose the incisors and guide grass toward the teeth-to-pad junction.1Forage Information System. How does Grass Regrow? This combination of split lip, sharp lower incisors, and soft upper pad lets sheep bite much closer to the ground than cattle can. It is one reason sheep can thrive on short, sparse pastures that would leave a cow hungry, and it is also why sheep can overgraze a field more severely if stocking rates are not managed.
Telling a Sheep’s Age by Its Teeth
Lambs are born with temporary (deciduous) incisors that gradually get replaced by wider, more durable permanent teeth. The replacement follows a predictable inside-out pattern: the two central incisors come in first, and the outer “corner” incisors arrive last. Farmers and veterinarians have long used this eruption sequence to estimate a sheep’s age without needing records.
A study tracking multiple breeds found that the permanent central incisors appear between about 12 and 18 months of age. The middle incisors follow at roughly 18 to 26 months, and the lateral pair comes in between 24 and 36 months. The outermost corner incisors, completing the “full mouth” of eight permanent incisors, erupt between about 32 and 44 months.3PubMed. Variability in the eruption of the permanent incisor teeth in sheep Research on indigenous African sheep found broadly similar timelines, suggesting these eruption norms are fairly consistent across breeds and environments.4Livestock Production Science. Age at permanent incisor eruption in indigenous goats and sheep in semi-arid Africa
In everyday farm language, you will hear sheep described as “two-tooth,” “four-tooth,” “six-tooth,” or “full mouth,” referring to how many permanent incisors have appeared. A two-tooth is roughly a yearling; a full mouth is typically three to four years old. After that point, the terminology shifts to descriptions of wear and loss rather than eruption.
How Sheep Graze Differently From Cattle
Cattle wrap their tongue around a clump of grass and pull, tearing it against the dental pad. Sheep rely more on their lips and incisors to gather forage, biting it off in more precise mouthfuls.1Forage Information System. How does Grass Regrow? This difference has real consequences for pasture management. Because sheep can crop plants right down to the crown, they are useful for managing weeds and maintaining short turf, but they can also damage pastures if left on the same ground too long.
Once the forage is swallowed the first time, it comes back up as cud for thorough grinding. The cheek teeth handle this job with a lateral chewing motion that smears food across those ridged molar surfaces. Research comparing the jaw mechanics of ruminants during initial chewing versus rumination found that the forces during the first round of chewing hay are actually higher than during rumination, but cud chewing involves longer, more sustained cycles.5PubMed Central. Mandibular corpus bone strains during mastication in goats (Capra hircus): a comparison of ingestive and rumination chewing Both phases put significant mileage on the teeth over a sheep’s lifetime.
What Wears Sheep Teeth Down
If you assumed that chewing tough grass fibers is the main thing wearing down sheep teeth, you would be in good company, but the evidence points in a different direction. The real culprit, at least for the incisors, is dirt. Sheep grazing on short pastures inevitably pick up soil with every bite, and the mineral particles in that soil are intensely abrasive.
New Zealand research tracked tooth wear and the soil content of sheep feces across farms and seasons. Wear was lowest when soil in the feces was low and peaked when soil content climbed. The worst wear hit in late winter and early spring, when pastures were short and grazing pressure was high, pushing sheep to bite closer to the ground and ingest more dirt. At peak periods, some animals had feces containing over 40 percent soil.6New Zealand Journal of Agricultural Research. Wear of sheep’s Teeth A companion study comparing farms with different wear rates confirmed the pattern: the farm with the highest tooth wear also had the highest soil content in feces, while the low-wear farm had the least.7New Zealand Journal of Agricultural Research. Wear of sheep’s teeth
What about plant silica? Grasses contain tiny glass-like structures called phytoliths, and for a long time researchers suspected these were the main source of tooth abrasion in grazing animals. Testing, however, showed that phytolith hardness ranged from about 51 to 211 on the Vickers scale, while sheep dental enamel measured between 293 and 357, meaning the enamel is substantially harder than the plant silica it encounters.8ScienceDirect (Journal of Archaeological Science). Do silica phytoliths really wear mammalian teeth? Soil particles, by contrast, contain quartz and other minerals that are harder than enamel. The upshot is that pasture management and soil type matter far more for tooth longevity than the type of grass being grazed.
Broken Mouth and Why It Ends a Ewe’s Career
As sheep age past about five or six years, their incisors progressively wear down, loosen, and eventually fall out. The condition where incisors are missing, broken, or spread apart so badly that they no longer meet the dental pad effectively is called “broken mouth.” It is one of the most common reasons breeding ewes are culled from flocks worldwide.
The productive life of a breeding ewe is essentially determined by the state of her permanent incisors and a farmer’s judgment about whether she can still graze well enough to maintain condition and raise lambs.9Elsevier / ScienceDirect. Incisor development, wear and loss in sheep and their impact on ewe production, longevity and economics: A review The progression from worn incisors to tooth loss involves a cascade of problems: as molars wear unevenly, the bite alignment shifts, increasing trauma on the remaining incisors during rumination. At the same time, grazing on rough or sandy pastures adds mechanical stress that loosens teeth further.10ScienceDirect (Journal of Archaeological Science). Incisor development, wear and loss in sheep and their impact on ewe production, longevity and economics: A review
The nutritional consequences are measurable. A study of Dohne Merino ewes found that greater incisor wear was significantly associated with lower bodyweight and poorer body condition, regardless of the animal’s age.11PubMed Central. Assessing the relationship between incisor wear, age, and body condition in Dohne Merino ewes (Ovis aries) A ewe that cannot crop grass efficiently simply does not eat enough, and that shortfall compounds through pregnancy and lactation when energy demands are highest. On farms where pasture is abundant and soft, a broken-mouth ewe may scrape by for another season. On hill country or short, sandy pastures, the same animal drops condition quickly.
Periodontal Disease and Calculus Buildup
Tooth loss in sheep is not purely mechanical. Like humans, sheep develop periodontal disease: infection and inflammation of the tissues supporting the teeth. Signs include calculus (tarite buildup), recession of the gum and bone around the tooth roots, new bone formation on the jaw surface, and teeth lost while the animal is still alive. Research examining both sheep and cattle skulls documented that the incidence of calculus and the degree of bone recession increase with age, and that these conditions tend to cluster together.12PubMed Central. Periodontal disease in sheep and cattle: Understanding dental health in past animal populations
Periodontal disease compounds the wear problem. A tooth already shortened by abrasion is more vulnerable if the surrounding bone is also receding, and inflammation weakens the ligament holding the root in its socket. For farmers, this means that tooth condition as assessed by simply looking at the visible crown may underestimate the problem; a tooth can look acceptable from the front while the root attachment beneath the gumline is failing.
Fluorosis and Enamel Damage
Environmental fluoride exposure is an underappreciated cause of dental problems in sheep. In areas near industrial fluoride emissions or with naturally high fluoride in water, sheep can develop dental fluorosis, a condition that weakens and pits the enamel during tooth formation. Experimental dosing of sheep with fluoride produced visible breaks and pitting in the enamel of nine out of ten treated animals, with damage ranging from surface roughness to extensive enamel loss with ledge formation along the tooth.13Archives of Oral Biology. Histological, macroscopic and microhardness observations of fluoride-induced changes in the enamel organ and enamel of sheep incisor teeth
Even prolonged low-level fluoride exposure causes problems. Research using low daily doses found that all treated teeth developed diffuse opacities similar to those seen in human fluorosis, with some teeth showing disordered enamel crystal structure under electron microscopy.14Archives of Oral Biology. The macroscopic and scanning electron-microscopic appearance and microhardness of the enamel, and the related histological changes in the enamel organ of erupting sheep incisors resulting from a prolonged low daily dose of fluoride Fluorotic enamel is softer and more porous than normal enamel, so affected teeth wear down faster once the animal begins grazing. In practice, this means a sheep in a high-fluoride area may reach broken-mouth condition years earlier than its genetics or pasture quality would predict. For flocks near smelters, brick kilns, or volcanic-fluoride zones, dental checks need to start earlier and happen more often.
Jaw Defects That Sheep Are Born With
Not all dental problems in sheep develop over time. Some lambs are born with brachygnathia inferior, commonly called “parrot mouth” or “monkey jaw,” where the lower jaw is shorter than normal and the incisors do not meet the dental pad properly. A breeding trial with East Friesian milk sheep found that 37 out of 60 lambs born to affected parents showed varying degrees of this jaw shortening.15PubMed Central. Review of literature and results from test matings of East Friesian milk sheep affected with brachygnathia inferior The condition worsened as the lambs grew, and severely affected animals developed ulcers on the palate and stunted growth. Some also had abnormal incisor positioning, twisted lower jaws, and ear deformities, suggesting the underlying genetic defect affects more than just jaw length.
Because the condition has a strong hereditary component, most breed societies recommend against breeding animals with noticeable jaw misalignment. A mild underbite might not prevent a ewe from grazing adequately on lush pasture, but it will reduce her efficiency on anything less forgiving, and she will pass the trait on. Rams are usually the focus of selection pressure because a single ram with the defect can spread it through dozens of offspring in one breeding season.
How Farmers Use Teeth to Make Flock Decisions
In commercial sheep operations, checking teeth is one of the most routine hands-on assessments a farmer makes. Ewes are typically “mouthed” once a year, usually before mating or weaning, and sorted into groups based on incisor condition. Animals with a full set of well-aligned, moderately worn incisors stay in the breeding flock. Those with heavily worn, loose, or missing teeth are flagged for culling or moved to easier pasture where they can still eat enough to maintain condition.
The economics are straightforward but harsh. A ewe with failing teeth eats less, loses body condition, produces less milk, and raises lighter lambs. Keeping her costs the same in pasture and management as keeping a sound-mouthed ewe but returns less. The challenge is that the subjective nature of the assessment means different farmers draw the line at different points. There is surprisingly little published data on how consistently farmers cull for dental reasons or whether earlier culling actually improves flock profitability over time.9Elsevier / ScienceDirect. Incisor development, wear and loss in sheep and their impact on ewe production, longevity and economics: A review
Some farmers try to extend the useful life of worn-mouthed ewes by moving them to softer, more abundant pasture in the final year or two. Others maintain a “hospital paddock” for older ewes with dental issues, offering supplementary feed during late pregnancy and lactation. Whether these strategies pay off depends heavily on how many extra lambs the ewe can produce relative to the cost of special management. On extensive hill farms where individual ewe attention is impractical, strict age-based culling at five or six years is the simpler norm.
Practical Pasture Choices That Protect Teeth
Because ingested soil drives most incisor wear, the single most effective thing a farmer can do to preserve tooth life is manage grazing to reduce soil intake. That means avoiding overstocking during wet months when pastures are short, because sheep forced to bite into muddy, close-cropped turf pick up far more grit per mouthful. Rotational grazing that maintains adequate pasture length, particularly during winter and early spring, reduces how much soil ends up in each bite.
Soil type matters as well. Sandy or volcanic soils containing quartz particles are harder on teeth than clay-heavy soils. Farms on abrasive soil types in New Zealand and parts of Australia are notorious for producing broken-mouth ewes two or three years earlier than farms on softer ground. In those environments, breeding for slower-wearing teeth, choosing breeds with harder enamel, or simply accepting a shorter productive life for ewes are all part of the management calculus.
Supplementary feeding during periods of short pasture is another tool. Providing hay, silage, or grain when paddocks are grazed down means sheep do not need to crop every last blade from the soil surface. It is an additional cost, but on farms where premature tooth loss is cutting a year or more off a ewe’s productive life, the math can work in favor of feeding rather than replacing animals earlier.