The most important point to remember about ageing a horse by its teeth is that it is not accurate! In younger horses (less than 10 years old) a reasonable estimate of age can be made by looking at the stages of eruption of the temporary and permanent incisors, and by looking at the incisor tables (grinding surfaces), which change in appearance as the incisors wear down throughout the horse’s life.
However, in older horses, estimates of age may be out by several years. In many respects, a horse is as old as it feels, and if your horse is bright, healthy and eating well, you shouldn’t worry when someone tells you that it has the teeth of a forty year-old. They may be many years off the mark!