Determining a Horse’s Age by its Teeth

: We are often called out by clients to check a horse they are interested in purchasing before they buy. As part of a pre-purchase exam, all horses should have their dentition checked. We have found broken teeth, broken jaws that have healed, and severe dental and oral diseases during these pre-purchase exams. One of the main things our clients are interested in knowing is the horse’s true age. We often see horses that sellers claim are 10-12 years old; in actuality, they are closer to 20 years in age based on their teeth.

Horses are characterized as grazing animals, meaning they are designed to eat mostly grass. Horses generally graze upwards of 10 hours a day in the wild, eating lower quality forages. Horses are also designed to eat with their heads down. Feeding out of raised feed tubs can lead to numerous dental issues, so we encourage clients to feed in tubs off the ground, hay included. You can also use low-hanging hay nets if your horse is stalled during the day or there isn’t much grass in the field. Changing a horse’s natural way of eating can also affect how their teeth wear.

Foals have a set of deciduous, or “baby,” teeth. They get a full set of incisors and the first 3 premolars before shedding those and developing their permanent dentition. Foals can be born with their first deciduous incisor already erupted, or it may erupt shortly after birth. Their remaining incisors erupt at 4-6 weeks, and 6-9 months, respectively. The deciduous premolars erupt within the first 2 weeks ¹. Teeth are considered “in wear” when they come into contact with the tooth opposing it. (insert picture of younger horse teeth). Occasionally, these baby teeth (also called “caps”) can become retained as the permanent teeth emerge. Fortunately, they are typically easy to remove with a little elbow grease and don’t cause any long-term damage or cosmetic effects. If left, however, they can form longer roots and make for some interesting looking smiles.

The permanent teeth begin erupting at 2 ½ years, with the central incisors, and continue outward each year. All permanent incisors are fully erupted between 4 ½ – 5 years. The canines erupt around 5 years of age. The shape of the incisors also helps determine a horse’s age. Horses less than 11 years old have a rounder shape to their incisors². As the horse ages, the incisors develop a more triangular shape, with older horses having almost a cheesecake appearance. (insert comparative picture of young vs old)

Teeth are made up of cementin, dentin, and enamel. As the horse eats and ages, the teeth get worn down in a set pattern. The “cup” is the center of the infundibulum, which is a groove on the tongue side of the tooth (see picture). Wear of the occlusal, or chewing, surface causes the cup to get smaller, and eventually disappear from all lower incisors between 6-8 years of age beginning with the central incisor. This leaves the “enamel spot” in its place. The enamel spot is the deepest part of the infundibulum. The “dental star” corresponds with the pulp cavity and appears at 8 years of age in the first incisor. It appears as a line and then changes to a large, round spot as the occlusal surface is worn further. It is still visible after the cup and enamel spot have been worn away².

Galvayne’s (pronounced Gal-veins or Gal-vey-nees) groove is useful in the older horse to estimate age. It appears near the gumline of the third incisor around 10 years of age, progressing to half way down at 15 years, and completely to the bottom of the tooth around 20 years. The groove then regresses from the gumline, progressing halfway down by 25 years. By 30 years old, the groove is completely gone². (insert groove picture with age)

By combining all of these indicators, we are able to narrow down a horse’s age to within a few months to years. Some horses do have individual variation, such as the 25 year old pony whose teeth look like she’s in her teens, or the 14 year old horse who looks like he’s 20. Bad habits such as cribbing can also prematurely wear down the incisors and make a horse appear older. If you have a question about your horse’s true age, give us a shout at 727-484-4473!

Written by: Dr. Morgan Bosch, DVM