You can tell
how old a horse is fairly accurately up to age 10 by their teeth. A horse
has all its teeth by the age of 5. After that, they just get longer. Determining
whether they are first teeth, permanent teeth, the presence of incisor teeth,
the length and slope of teeth all help to indicate a horse's age. It is more
difficult to tell the age of an adult horse by the teeth.
side profile of teeth
Horses' teeth are often used to estimate the animal's age, hence the saying "Don't look a gift horse in the mouth".
At five years of age a horse has forty teeth:
24 molars or jaw teeth,
12 incisors or front teeth,
4 tusks or canine teeth between the molars and incisors; these are generally found in all horses but sometimes fail to erupt and remain in the jaw. An old wives tale thought that only colts (and therefore stallions and geldings) had them, but this is not true.
Some horses also have wolf teeth - a throwback to the old fighting tooth. If present these can cause problems in the bitting of the horse as they are where the bit sits.
At birth (or within six days) only the two nippers or middle incisors appear.
At one year old all the incisors of the first or milk set of teeth are visible.
At about the age of 2 1/2 years a horse sheds baby teeth.
Before three years, the permanent nippers have come through.
At four years old, the permanent dividers next to the nippers have emerged.
At five the mouth is perfect, the second set of teeth having been completed.
At six the hollow under the nippers, called the mark, has disappeared from the nippers, and diminished in the dividers.
At seven the mark has disappeared from the dividers, and the next teeth, or corners, are level, though showing the mark.
At eight the mark has gone from the corners and the horse is said to be aged. After this time, indeed good authorities say after five years, the age of a horse can only be conjectured. But the teeth gradually change their form, the incisors becoming round, oval, and then triangular. Dishonest dealers sometimes "bishop" the teeth of old horses, that is scoop them out, to imitate the mark: but this can be known by the absence of the white edge of enamel which always surrounds the real mark, by the shape of the teeth, and other marks of age about the animal.
Human teeth don't keep growing throughout a person's life, but horses' teeth
do. As they grow, they develop sharp edges and can become quite uneven, making it difficult and painful for a horse to chew its feed effectively, hold a bit in its mouth comfortably, or even accept the pressure of a noseband.
"Floating" means smoothing and contouring a horse's teeth with a file (called a "float"). It's something
that is routinely done by veterinarians, once or twice a year, or more often if the horse requires it.