Next examine the mouth to ascertain the age. Yearlings and two-year-olds are alike in mouth, and must be judged by general appearance. At three years old, the horse has four horse teeth, two above, and two below, in front of the mouth, which supply the place of the sucking teeth. At four, he has eight horse teeth, four above, and four below, having the corner teeth only sucking teeth. At five years old these are gone, and the mouth is up; that is, all the teeth are horse teeth, and the tusk is up on each side of the mouth, A dark mark, or hollow, is generally observable in all the teeth in the bottom jaw at just five years old; and the tusks are concave in their inner surface. At six, the two middle teeth have quite lost this mark, and the tusk is higher up, and longer, and not so concave. At seven, the next two teeth have lost it, and the corner teeth only have the mark left in them. At eight it has grown out of these, and no mark is left at all. The tusks also become longer, and instead of being concave in their inner surface, become convex; the horse is then termed aged. There is a great deal of difference in the mouths of horses: some have lost the mark in all, except the corner teeth, even as early as five years old; others have the front teeth in the top jaw, projecting over the bottom teeth, at the same age; and I have seen horses at seven years old, with the corner teeth appearing like those of a five-year-old. You may form some idea of the age from the appearance of the mouth in general, when the marks are no longer visible. If the corner teeth do not appear long, and running forward, as it were, to the front of the mouth; if they retain their square shape, and shut well together; if the tusks are not blunt, and have the least concavity in their inner surface, you may conclude that the horse is not very old, particularly if his head be not gray, and not very hollow above the eyes; though this latter shape sometimes exists in young horses. A concave tusk is the most certain criterion of youth; and as mares have no tusk at all, they must be judged with reference to what I have said about the corner teeth. It is here necessary to mention, that the difficulty of acquiring an accurate knowledge of the age of horses by their teeth, is very much increased by the tricks that are practised.

It is generally allowed that no horses are fit for work till at least five years old; and it is a common custom with great breeders in the north, and with many dealers, to pull out the sucking teeth when the animal is rising four years old; the mouth is forced by these means, for the horse-teeth succeeding soon after the operation, the animal appears to be a five-year-old. To detect such deception, regard must be paid to the tusk. Every horse, upon attaining the full age of. five, has the tusk completely up on each side of the mouth; but in forced five-year-old mouths the tusk is only just making its way through the gums. There frequently exists also in the latter an irregularity in the front teeth, as well as a backwardness in the growth of the tusk. Forced mouths vary in their appearance according to the time of performing the operation; and the habit of observing horses' mouths will alone enable you to ascertain where any artifice has been practised.