Sheep generally lack top teeth in the front of the mouth. As a grazing ruminant, the sheep’s dental structure is highly specialized and adapted for a diet of coarse, fibrous plants like grass and hay. This unique arrangement allows the animal to efficiently harvest and process large quantities of forage. An adult sheep has a total of 32 permanent teeth, but these are distributed unevenly between the upper and lower jaws, reflecting a different approach to biting and chewing than seen in many other mammals.
The Specialized Upper Jaw and the Dental Pad
Sheep lack upper incisors and canines. The space where these teeth would normally sit is occupied by a dense, hard structure known as the dental pad. This pad is a thick, fibrous cushion of tissue that forms the front of the upper jaw, providing a firm, toothless surface.
The dental pad functions as a stationary surface against which the lower front teeth press. When a sheep grazes, it uses its lower incisors against the tough dental pad to effectively shear and cut blades of grass. The tongue also plays a significant role, wrapping around the plant material to pull it toward the mouth before the cutting action occurs.
The presence of the dental pad is a defining characteristic of ruminant dentition, which includes cattle and goats. This anatomical feature ensures that the animal can secure a mouthful of grass before the lower teeth sever it. This design is optimized for a grazing lifestyle where efficiency in food collection is paramount.
The Function of Lower Incisors and Canines
While the upper jaw lacks front teeth, the lower jaw contains a full set of specialized incisors and canines. An adult sheep has eight teeth in the front of its lower jaw, commonly referred to as the incisor battery.
The four pairs are not all true incisors; the outermost tooth on each side is technically a canine, but it functions exactly like the incisors. These teeth have wide, asymmetrical crowns designed specifically for cutting. They align perfectly to meet the upper dental pad, creating a powerful scissor-like action when grazing.
These lower incisors are not deeply rooted in the jawbone compared to the teeth of many other species. This shallow housing allows for flexibility that helps the sheep adapt to the varied textures of grass and soil encountered during continuous grazing. The combined action of the lower incisors and the upper dental pad allows the sheep to efficiently crop grass.
Grinding Power The Role of Molars
The true teeth in the upper jaw are located at the back of the mouth, far from the dental pad. These are the premolars and molars, collectively known as the cheek teeth. An adult sheep possesses a total of 24 cheek teeth, with six on each side of both the upper and lower jaws.
These molars and premolars are broad and feature deep ridges on their surfaces. This structure provides a substantial grinding area necessary for the mechanical breakdown of tough plant cellulose. Chewing occurs laterally, moving the lower jaw side-to-side to grind the forage.
This grinding action is necessary because sheep, like all ruminants, must reduce the particle size of their food before it can be effectively digested by stomach microbes. They chew their cud, which involves regurgitating partially digested food and re-chewing it multiple times to ensure maximum nutrient extraction. The robust structure of the molars makes them perfectly suited for this demanding, repetitive grinding work.
How Teeth Reveal a Sheep’s Age
The front lower incisors serve as a reliable indicator of a sheep’s age, a practice often used in animal husbandry. Lambs are born with temporary, or milk, teeth that begin to erupt within the first week. By two months of age, the lamb typically has all eight milk teeth in the lower jaw.
As the sheep matures, these temporary teeth are gradually replaced by permanent incisors, which appear in pairs from the center outward. The first pair of permanent incisors typically erupts around 15 to 18 months of age. A sheep is referred to by the number of permanent incisors it has. A two-tooth sheep has one pair, a four-tooth has two pairs, and so on.
A sheep is considered to have a “full mouth” when all eight permanent incisors have fully erupted, which usually occurs between three and four years of age. After this point, age estimation relies on the degree of wear, splay, and deterioration of these permanent teeth. As the sheep ages further, its incisors begin to spread out, wear down, or even break, a stage commonly called “broken mouth.” An extremely old sheep that has lost its incisors due to excessive wear is sometimes called a “gummer,” relying only on its molars to process food.