When the horse reaches seven years of age, the cups have not only disappeared from the central nippers, although small, darkish spots may be seen, but they have nearly or quite disappeared from the laterals as well. The corner teeth still retain the cups, though they are shallow, which is evidence that the teeth have been in wear two years, and that in another year the cups will have nearly or quite disappeared. (Fig. 71.) It will be noticed that, from the time when the teeth in the lower jaw are well up and in wear to the time the cups have virtually disappeared in the lower jaw, is three years. It is well to keep this in mind. The teeth in the upper jaw retain their cups for a longer period.

A side view of a seven-year-old mouth shows one marked characteristic. (Fig. 72.) The lower corner teeth seldom extend as far backward as the upper ones do. Only in very rare cases do all of the four corner teeth meet at the corners accurately; in which case the posterior corners of the upper incisors are not worn down level with the rest of the teeth. The result is, the face of the tooth in wear recedes, while that part of the tooth not in wear projects downward, forming more or less of a "notch." Sometimes no distinct notch is apparent. However, by close inspection, it can be seen that the face of the upper corner tooth, where it meets the lower one, is not straight, as it was when the horse was six years of age, but slightly concave. If the teeth should chance to meet at the corners more accurately than shown in Fig. 72, then no notch will be formed; nevertheless the upper corner tooth will be slightly concave, though not so marked as shown in the above figure. However, it is seldom that this distinguishing notch is not forming or formed on one or the other of the upper corner teeth at the age of seven years.

Side view of the nippers of a seven year old horse.

Fig. 72. Side view of the nippers of a seven-year-old horse.

The Horse s Teeth 71

At eight years of age, the marks or cups have disappeared from the teeth of the lower jaw. However, slight dark-colored indentations are still present in the corner teeth, but they are not pronounced enough to be called cups. {Fig. 73.) The shape of the teeth has radically changed. Turn to Fig. 74, and note the cross-section of a front incisor tooth when it has been in wear five years, - that is, when the horse is eight years old, as compared with the teeth of a five-year-old horse. At eight years of age there are indications that the bones of the jaw and the teeth have already ceased to enlarge. In some cases they show a slight shrinkage and the contour of the lower jaw has become less rounded. Compare Fig. 73 with Fig. 65. Finding that the cups have nearly or quite disappeared from the lower jaw, we proceed to examine the upper nippers. It is not easy to get a clear view of the upper nipper teeth of a restless animal. If the horse is eight years old the cups will still be present in the upper center nippers, but they will not be deep. If the teeth be viewed from the side, Fig. 75, they will appear somewhat long, and will meet at a sharper angle than they did when the horse was but four years old. As the years go by, the angle of the teeth increases. At four years of age, the upper and lower teeth meet nearly vertically with each other, at twenty at an angle of nearly forty-five degrees. The tusks are becoming constantly larger, rounder and blunter as the years advance. Compare Fig. 75 with Fig. 66, and the notches in the corner teeth have become pronounced.

Cross section of an incisor tooth, showing how the shape changes with advancing years.

Fig. 74. Cross section of an incisor tooth, showing how the shape changes with advancing years.

At nine years of age, the cups will have disappeared from the upper center incisors, and will be shallow in the laterals but fairly deep in the corner teeth. The cups do not disappear at such regular intervals in the upper teeth as they do in the lower ones. Therefore, it is not always possible to tell the age of a horse within a year or two, after he has passed his eighth year. However, the character, shape and angle of meeting of the incisor teeth may all be used to assist the judgment in determining age. As has been formerly stated, horses having dense, hard bones and hoofs are likely to be rated younger than they are, after eight years of age, when judged by the teeth alone; while horses of softer bony structure are likely to be judged older than they are.

At ten years, the cups have disappeared from the upper lateral teeth, the notches in the corner upper incisors have become enlarged, and all the signs of advancing age, as described above, are becoming marked.

The incisor teeth of an eight year old horse.

Fig. 75. The incisor teeth of an eight-year-old horse.

Usually, when the horse reaches his eleventh year, all the cups have disappeared; though it is not uncommon to find shallow cups in the upper corner teeth of smallish dense-boned horses up to thirteen or even fourteen years of age. However, the shape and the angle of the incisors prevent a close judge from being much deceived. After the horse has passed his twelfth year, the matter of two or three years counts for but little; since all horses have then passed their prime, and, while they may, for certain purposes, be as efficient as they were when young, the time is fast approaching when the capital invested in the horse will be lost. The value of a horse is modified by the number of years which is likely to elapse before his value reaches the zero point. For instance, a ten-year-old horse may be, and usually is, able to perform more service than a five-year-old; but the five-year-old may be able to perform twelve years of efficient service, while, if a horse be ten years old, there would be but seven years of service before the capital stock invested would be sunk. Then, too, old horses are likely to be more sluggish than young ones. All things considered, it is seldom wise to purchase an old horse unless the price is low; in which case it matters little whether the horse is fourteen, fifteen or sixteen years of age. One's judgment of the value of a horse at these ages should be founded on general appearances and on activity shown, rather than on age, which cannot be accurately determined by an examination of the teeth. One may distinguish between a horse moderately old and one that is very old; but after the horse reaches his twelfth year the teeth do not accurately indicate the age.