Although it is commonly believed that a horse’s age can be determined by its teeth, this is not entirely accurate. Unlike the rings of a tree that show annual growth, a horse’s teeth do not provide a definitive indicator of age. However, examining a horse’s teeth can provide a rough estimate of its age if its birthdate is unknown. The accuracy of this method decreases as the horse gets older due to various factors that can affect the condition of the teeth, such as diet, grazing conditions, maintenance, vices, and genetics. As a result, estimating a horse’s age by its teeth is not entirely reliable, but it can still provide a general range of the horse’s age.
Baby Horse Teeth
Foals begin to develop deciduous teeth, also known as milk teeth, shortly after birth. These teeth are entirely replaced by the final set of milk teeth when the foal is approximately nine months old. Permanent teeth start to grow when the horse reaches two to three years of age. Occasionally, horse owners may find a shed tooth in a feeder or on the ground. The milk teeth are gradually shed, and all of the permanent teeth emerge by the age of five. Distinguishable by their shorter length and paler color, milk teeth differ from permanent teeth.
Adult Horse Teeth
Determining a horse’s age can be done relatively accurately by observing the eruption times of specific teeth, including the upper central incisor (2.5 years), upper middle incisor (3.5 years), and upper corner incisor (4.5 years) until the age of 5. Additionally, the concave “cups” on the new permanent teeth and Galvayne’s groove, a groove that grows out on the outer vertical surface of the upper corner incisor, are other indicators of a horse’s age. However, a hook at the rear end of the upper corner incisor visible at 6-7 years and 11-13 years is not always definitive in determining a horse’s age.
As horses wear their teeth down through grazing, the concave surfaces become flatter. This process occurs more quickly in horses grazing on sandy ground than those fed hay grown on clay soil. By age 11, a horse’s teeth are usually worn flat. The Galvayne’s groove begins to appear at the gum line around age 10 and continues to grow until it reaches the entire length of the tooth by age 15. It eventually disappears by the mid-20s as the tooth wears away naturally. Therefore, monitoring the progression of Galvayne’s groove is a reliable method to estimate a horse’s age from 10 to 20 years old.
Senior Horse Teeth
As a horse ages, the angle of its teeth increases, causing the teeth to become more angled and the upper corner incisor to become taller than wide. This results in the saying “long in the tooth” as the length from the gum line to the chewing surface increases. Additionally, the shape of the teeth changes from oval to more angular, and the color of the teeth tends to yellow and become stained. At some point in their late 20s, horses may start losing teeth because they have a limited lifespan. While domestic horses may outlive the lifespan of their teeth, losing teeth can negatively impact their health, making it harder for them to chew tougher hays and grasses. As a result, older horses may require a diet tailored to their specific needs.
Extra Horse Teeth
Extra teeth such as wolf teeth and tushes or canines may grow in the toothless bar of a horse’s mouth, located between the front and back teeth. In some cases, these teeth may need to be removed if they cause discomfort for the horse or interfere with the use of a bit. These teeth typically appear by the time the horse reaches five years of age, but not all horses will develop them, and for some, they may not cause any issues.
Care of Horse Teeth
Due to the uneven wear of a horse’s teeth and the continuous growth throughout their life, it’s important to have a veterinarian or equine dentist check on your horse about once per year. The horse may need to have their teeth floated, which involves filing down any sharp edges or hooks that may impede their ability to chew properly or wear a bit or hackamore comfortably.
Horse Teeth: Comprehensive Diagrams and Explanations
Although this is a brief overview of horse aging by teeth, there are more comprehensive resources available from various university agricultural extensions. These fact sheets include detailed diagrams of horse teeth at every stage of life, making it easy to compare actual teeth to the pictures. The University of Nevada Cooperative Extension offers a helpful PDF file that can be printed out and taken to the barn, while the University of Missouri has a similar online resource complete with diagrams and explanations.