Equine: Dentition

Heterodontous, Diphyodontous

Equines are both

Heterodontous

which means that they have teeth in more than one shape

Diphyodontous

have two successive sets of teeth, the deciduous ("baby teeth") and permanent sets.

5 shapes

How many shapes of teeth are there in a horse

Deciduous, Permanent

Two successive set of teeth in Equine

36 - 44 teeth

A fully developed horse of around five years of age will have between

Incisor Teeth

at the front of the mouth, used primarily for cutting or gripping food, most often grass, whilst grazing.

Nippers

Another name for Incisors

12

How many incisors are present in the horses mouth

Incisor Teeth

They are also used as part of a horse's attack or defence against predators, or as part of establishing social hierarchy within the herd.

Centers, Pincers, Nippers

The two central pairs of incisors both above and below are called

Intermediates, Laterals

The four teeth adjacent to these two pairs are called

Corners

Outer four teeth of the incisors are designated as

Canine Teeth

some, but not all, horses have this teeth

0 - 4

Number of canine teeth in horses

Tusk, briddle teeth, Eye teeth, Dog Teeth

Canine teeth are also known as

Tush

Deciduous precursor of Canine Teeth

Fewer than 28%

Female (mares) that have canine teeth

1 - 2 may be partially erupted

Canine teeth in females

Cheek teeth

behind the interdental space or diastema

Disastema

Interdental space

Cheek Teeth

all horses also have twelve premolars and twelve molars

Jaw teeth, Grinders

Another term for Cheek teeth

Cheek teeth compensation

compensate for the constant grinding which wears away 2-3mm

per year.

2-3 mm

At what rate does horse teeth wear off every year

Hypsodont

horses have very long teeth that are referred to as "high tooth."

High Tooth

These teeth chew food bitten off by incisors, prior to swallowing.

Wolf Teeth

generally considered being the remnant of an earlier premolar; relatively small and serve no useful purpose.

Less than 10 mm in diameter

Size of wolf tooth

Wolf Tooth

Found in both sexes, they are located immediately forward of the first upper cheek teeth.

Permanent Counterpart

Though most wolf teeth are deciduous as a result of root resorption, they are not replaced by a

Incisors, Molars, Premolars

These teeth once fully developed, continue to erupt as the grinding surface is worn down through chewing.

4.5 - 5 inches long

A young adult horse's teeth are typically

2 - 3 mm per year

The rest of the tooth slowly emerges from the jaw, erupting about

Triadan system

which assigns a 3-digit number to a specific tooth.

1, 4, 6, 9, 11

Tooth Numbering in the Triadan System

• __ – Central incisor

• __ – Canine (whether present or not)

• __ – Second premolar (first cheek tooth)

• __ – First molar

• __ – Last molar (M3)

Age estimation

(1) eruption of deciduous and permanent teeth, (2) the shape and appearance of the occlusal surface of the lower incisors, (3) the bite alignment of the incisor arcades and (4) the presence of hooks and grooves on the upper corner incisors.

Lower incisors

The most appropriate teeth to estimate age in horses are the

5 years

When are horses considered as full mouth

Full mouth

means that all permanent teeth have erupted and are in wear.

6 - 9 months of age

When does wolf tooth erupt

Blind wolf teeth

Some wolf teeth never erupt through the gums. These are usually located 10-15 mms further forward than the site of normal wolf teeth.

4 - 5 years

Meanwhile, bridle teeth or canine teeth are a male characteristic, and usually erupt between ages

Temporary Incisors

possesses a definite crown, neck, and root

Temporaries

smaller than the permanent ones, and the surfaces of their crowns are whiter and have several small longitudinal ridges and grooves.

Permanent incisors

larger and more rectangular in shape.

Permanent Incisors

Their crown surfaces are largely covered with cement and have a yellowish appearance.

Upper Incisors

have two distinct longitudinal grooves on their labial surface, while the lower incisors have only one.

Progressive dental wear

causes an alteration of the occlusal shape of the incisors.

Occlusal surfaces

recently erupted incisors are elliptical, but with age they subsequently become trapezoid, round, and then triangular, with the apex toward the lingual side.

Equine incisor teeth

develop certain wear-related macroscopic features traditionally used to estimate age including the dental cup, enamel ring, mark and dental star.

Dental Cup, cup, infundibulum

deep indentures in the center of the young permanent teeth surfaces, usually appears at the age of 5.

Enamel Ring

The wall covering the infundibulum (and the mark) is also used to determine the age of the horse based on its disappearance

Mark, enamel spot

As the edges of the cups wear down through age and use, the depressions become shallower and eventually disappear, leaving a white surface with a small, dark central pit known as

Studying cups

this method is second in accuracy only to the appearance of permanent teeth in determining age.

Dental Stars

yellowish-colored brown secondary dentin spot that fills up the pulp cavity and appears at the occlusal surface as the incisor tooth wears. It appears labial to the cups.

Bite Alignment of the Incisor Arcades

The curvature of the dental arch formed by the lower incisive tables is also age related.

Semicircular

In young horses this arch is

Straight Line

In older horses this arch is

alveoli, undergo attrition

Additionally, the arch formed by the incisors of the opposing jaws (as they meet) changes as the teeth advance from their

Straight line

In young horses, the upper and lower incisors are positioned in

Hook

formed on the upper corners.

Galvayne’s groove

A more subtle indicator that can assist with aging the horse over 10 years of age is the

Sidney Galvayne

a 19th-century horseman born in Australia who gained recognition as an excellent judge of a horse's age by examining its teeth while traveling Europe in the 1880s.

Galvayne’s groove

This groove appears near the gum line of the upper corner incisor producing a vertical line.

Notch, Dove tail

Another subtle indicator on the same corner tooth is the 7 and 11 year hook or

Cribbing/Cribbiting/Windsucking

A bad habit of some horses in which the animal grasps the manger or other object with the incisor teeth, arches the neck, makes peculiar movements with the head, and swallows quantities of air.

Dental caps

deciduous cheek teeth that remain attached to the chewing surfaces of the permanent teeth after they have erupted.

Dental Caps

These caps are extremely sharp and may cut the cheek or tongue and interfere with eating. Occasionally, a cap becomes partially detached and rotates out to the side, where it damages the cheek and deforms the face.

Enamel Points

develop on the outer edges of upper molars and inner edges of the lower molars. This occurs when there is an incomplete overlap of the upper and lower molars and uneven wear on the grinding or biting surfaces during side-to-side chewing.

Impacted Teeth

tend to occur in horses with a foreshortened upper or lower jaw. These horses have insufficient room for the teeth to erupt normally. This forces the tooth to remain in the jaw bone, creating inflammation and even swelling of the bone.

Molar Hook

occurs as a result of misalignment of the upper and lower jaw so that the upper jaw lies ahead of the lower jaw. Consequently the front of the 2nd molar of the upper jaw does not wear against a lower tooth. The tooth continues to grow and forms a hook.

Monkey Mouth

the lower jaw is longer than the upper, and the lower incisors project beyond the uppers like a Bulldog. It is less common than parrot mouth. The horse may have trouble grazing or “nippin” grass.

Sow mouth, Undershot mouth

Another term for monkey mouth

Parrot Mouth/Overshot

the reverse of an undershot jaw— the most common malocclusion. In a horse with this deformity, the lower jaw is shorter than the upper jaw. In consequence, the upper incisors overhang the lower ones. Because the upper incisors are unopposed, they grow long like rabbit teeth.

Shear Mouth

In normal horses, the upper arcade is always wider than the lower arcade. This discrepancy is exaggerated. This produces long, extremely sharp shearing edges on the cheek teeth. An acquired type occurs in old horses that develop age-related changes involving the shape of the mandible.

Smooth Mouth

This is caused by equal wear of both the enamel and dentin and produces an absolutely smooth surface on the cheek teeth instead of the normal rough grinding surface.

Step Mouth

in horses with this disorder, there is an abrupt change in the height of adjacent premolars and molars. In many cases, a lost tooth leaves a space that permits an opposing tooth to grow out without meeting resistance.

Retained Dental Cap

Another cause of step mouth

Step Mouth

serious problem, because affected horses have great difficulty chewing and digesting their feed. Treatment involves rasping the elongated molars, using motorized equipment, at six-month intervals.

Supernumerary Teeth

due to splitting of the tooth buds resulting to one or two extra teeth (incisors or cheek teeth);

Dental Crowding

can result in tooth overgrowth and gaps between teeth that result in gum infection and tooth decay.

Wave Mouth

often occurs in conjunction with parrot mouth, retained dental caps or incisors that are too long.

Wave Mouth

These factors cause a variation in molar height without even contact and wear; some molars grow longer than other resulting in a wave-like appearance when the molars are viewed from the side

Wave Mouth

Mild cases may respond to floating the teeth at frequent intervals. In more severe cases, an attempt should be made to even the arcades by rasping, using motorized equipment.

Wolf teeth

found usually in upper arcade in front of 2nd premolar that often interfere with bit.

Floating, Rasping, Filing

done routinely once a year after a horse reaches 18 months of age.

Floating

Control the sharp edges and points present on the cheek side of the upper premolars and molars and on the tongue side of the lower premolars and molars. Also used to correct minor abnormalities of wear, such as lowering a tooth that has grown too long.

Bishoping

act of changing the appearance of equine teeth to make the horse look younger. This process can involve such processes as filing down the Galvayne's Groove or changing the shape or length of the teeth, or using silver nitrate to artificially create cups.