Introduction: When determining the age of a horse, the lower set of incisors are used. The first step is to determine if the horse has any permanent teeth. Horses, like humans, have deciduous (baby) teeth that fall out and are replaced by permanent (adult) teeth. Realize that as a horse ages, the accuracy of determining its age by using the teeth, declines. The following information and pictures will help a horse owner identify the approximate age of a horse. Pictures and text are adapted from the Official Guide For Determining the Age of the Horse, published by the American Association of Equine Practitioners.
Central Lower Incisor
Deciduous Incisors
Permanent Incisors
2 Years
2½ Years
3 Years
3½ Years
4 Years
4½ years
5 Years
7 Years
10 Years
15 Years
20 Years
Aging Horse Lower Incisors (In Years)
| Permanent (Adult) Teeth | Central Incisor | Intermediate Incisor | Corner Incisor |
| Erupts | 2.5 | 3.5 | 4.5 |
| In wear | 3.0 | 4.0 | 5.0 |
| Level | 5.0 | 6.0 | 7.0 |
| Cup gone | 6.0 | 7.0 | 8.0 |
| Dental star | 8.0 | 9.0 | 10-11 |
| Round in shape | 9.0 | 10.0 | 11-12 |
| Disappearance of enamel spot | 13-16 | Variable | Variable |
| Triangular in shape | 16.0 | 17.0 | 16-17 |
Bold identifies the more accurate characteristics