Horse Age by Teeth Chart: Estimating Age by Dentition

Aging by teeth is reasonably accurate in young horses and grows less precise with age. In the first five years, the eruption of milk teeth and then permanent teeth gives fairly reliable landmarks. From about six to ten years, wear patterns and cups help. Beyond the teens, estimates become rough, often within a range of several years, because diet, grazing surfaces, dental care, and individual variation all affect wear. It is a useful guide, especially for a horse of unknown history, but not an exact birthday.

Galvayne's groove is a darkened vertical line that appears on the outer surface of the upper corner incisors. It is one of the classic aging markers. The groove typically begins appearing at the gum line around age 10, extends about halfway down the tooth by roughly age 15, reaches the bottom of the tooth around age 20, then recedes from the top down, disappearing from the upper half by about 25 and gone entirely near 30. Like all dental markers it varies between horses.

Cups are the dark central hollows on the chewing surface of the incisors. As a horse wears its teeth through grazing, these cups gradually fill in and disappear, which helps estimate age. The lower (mandibular) incisors lose their cups before the uppers. Cups are generally gone from the lower central incisors around age six, the lower middle incisors around seven, and the lower corner incisors around eight, giving rise to the saying that a horse is smooth mouthed once the cups are worn away.

The 7-year hook, or Galvayne's hook, is a small hook-like projection that can form on the upper corner incisors at around age seven because the upper tooth slightly overhangs the lower one. It may wear away and then reappear later, around age 11 or so, which is why it is only a supporting clue rather than a definitive marker. Because it comes and goes and varies between horses, experienced examiners use it alongside cups, the shape of the chewing surface, and the angle of the teeth.

As a horse ages, the angle at which the upper and lower incisors meet when viewed from the side becomes increasingly sharp and slanted forward, rather than meeting nearly vertically as in a young horse. This change in the profile angle of the bite is one of the more reliable indicators of advanced age. Combined with the shape of the chewing surface, which shifts from oval to round to triangular over the years, the bite angle helps experienced examiners place an older horse in an approximate age range.

Indirectly, yes. Severely worn, loose, missing, or angled teeth, smooth mouths, and conditions like EOTRH or quidding (dropping balls of partly chewed hay) mean a horse can no longer grind long-stem forage well. That is a strong signal to consider soaked complete feeds or forage replacers so the horse still gets enough fiber and calories. A dental exam by a vet or equine dentist, not just a glance at the incisors, is the right way to assess chewing ability and guide feeding changes.

Use teeth as one input, not the whole answer. Dental aging gives a useful estimate, particularly under ten years old, but it can be imprecise in older horses and can even be deliberately altered. Combine it with any available records, registration papers, microchip or brand information, and a veterinary prepurchase exam. For an older horse, a vet's full dental and physical assessment tells you far more about usable years and care needs than the incisors alone ever could.