Dental Development of Horses
Each species of animal has its own unique type of teeth, depending on what food the animal normally eats. For example, a meat-eating animal such as a cat has quite different teeth than a horse, which eats grasses and grains. However, all domestic animals have 2 sets of teeth during their lives, as humans do: a set of deciduous (“baby”) teeth that fall out, and a set of permanent teeth that develop later.
Most horses have 28 deciduous teeth. Mature stallions have 40 to 42 teeth, while mature mares have 36 to 38 teeth. The difference is due to the fact that the canine teeth, which appear at around 4 to 5 years of age, are often not seen in mares. Deciduous teeth appear early—usually within 2 weeks of birth. The first permanent teeth to appear are the first premolars sometimes called “wolf teeth.” They are usually found in the upper jaw; however, they are sometimes found in the lower jaw as well. The permanent molars erupt at about 1, 2, and 3.5 years of age. The replacement of deciduous incisors and premolars by the permanent successors starts at about 2.5 years of age. All permanent teeth are usually present by the time the horse reaches 5 years of age (see Table: Equine Dentition).
In horses, the structure of the teeth allows the age of the animal to be estimated by the eruption times and general appearance of the teeth, particularly the lower front teeth (lower incisors). However, tooth appearance is affected by individual and breed variations and differences in environmental conditions, so it does not provide an exact measure (see Table: Estimation of Age of Adult Horses by Examination of Teeth).
Equine incisor teeth develop certain wear-related visible features that are traditionally used for estimating age. For example, the “dental star” is a yellowish-brown mark that appears at the bite surface as the tooth wears. Its shape and position, as well as the appearance of the white spot in its center, are related to age. The shape, size, and time of disappearance of indentations on the bite surface are additional indicators of age. Progressive dental wear also causes an alteration of tooth shape, and the angle of the teeth changes with age. In young horses, the upper and lower incisors are positioned in a straight line. With increasing age, the angle between upper and lower front teeth becomes sharper as the teeth wear away.
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