Figs. 76 and 77 graphically illustrate the appearance of the teeth of an old horse. The incisor teeth have become nearly triangular and they show long wear The tusks are large, blunt and round; the notches in the corner teeth, long and deep; the front ends of the teeth have been broken off, and they meet at an acute angle. They may have grown out so long as to prevent the double teeth from meeting; in which case the horse will spit out his food after he has extracted some of its juices by imperfect mastica tion. If the incisor teeth be rasped off on their posterior edges, the grinders will then meet and lite will be somewhat prolonged. It is humane either to do this or to destroy the animal, rather than to let it die by slow starvation.
Fig. 76. The lower incisor teeth of an old horse. Note the shape and length of them.
Having given somewhat lengthy and detailed instructions for determining the age of horses by an inspection of their teeth, it will assist materially in understanding the instructions if the teeth be studied in a different way. Fig. 78 shows an entire permanent incisor tooth. It will be observed in the left-hand cut, that the face of the tooth has not yet been in wear and that the inside of it is not fully up. The cup is about three-eighths of an inch deep. It is of such a curvature that when the opposite tooth meets it they will come together much as the jaws of an ordinary pair of pincers do, and not like the jaws of a pair of tongs.
In the second cut from the left is shown the same tooth, the cross line indicating how much of the tooth has been worn away by one year's wear. Nearly or quite one-third and the broadest part of the cup is gone. In the third cut from the left, the cross line shows how much of the tooth will be worn away when it has been in wear two years. The fourth cut from the left shows a front incisor which came up at three years of age and has been in wear three years. The cup has nearly or quite disappeared, which occurs at six years of age. When the horse reaches nine years of age, the cut shows that about three-eighths of an inch of the tooth has been worn away below the cup. At twenty years, the tooth shows much wear. The direction of wear, as shown by the cross line, has changed. Note the angle and how different it is from the visible angle of the teeth of a young horse.
Fig. 77. A side view from life of the nippers of an old timer.
Fig. 78. Shows the wear of an incisor tooth and why the cups, or marks, disappear as age advances. The lower nippers wear away about one-eighth of an inch each year. The upper incisors wear away more slowly.
Turn back to Fig. 74, as it will assist the eye and the judgment in distinguishing between a tooth which has just come in wear and one that has been in wear four, eight, fourteen and twenty years, respectively, as shown by the dotted lines. It also shows clearly the marked changes which occur in the shape of the teeth when viewed in cross section. At from eleven to thirteen years, as has been stated, all the cups disappear from the upper incisors, after which there is difficulty in accurately determining the age. However, if the shape of the teeth is observed critically (Fig. 74), it will not be at all difficult for a novice to distinguish between a horse just past his prime, an old horse and a very old horse.
Note - Throughout this chapter the terms "temporary teeth" and "milk teeth," also the words "incisors" and "nipper.-" have been used synonomously. This is in recognition of the fact that these terms are so used by many good horsemen.