THE HORSE-ANATOMY AND PHYSIOLOGY. 



633 



Fig. 15 shows the triangular form disappearing, especially 

 in the nippers. The corner teeth retain yet something of the 

 triangular form; the tushes are becoming more blunt; the teeth 

 longer and further from a direct line, or from bearing one upon 

 another. 



FlG. 16. MOtTTH AT TWKNTT YEARS. 



The corner teeth now have become triangular deeper from 

 front to back part. At twenty-one, the angles have disappeared 

 from the teeth, and all are oval; but this is reversed, being 

 deeper from outward, inward. As the horse advances in 

 years the teeth grow thicker than they are broad, and as this 

 thickness increases, the space between the teeth increases. As 

 the teeth increase in length, they become of a dirty yellow, with 

 occasional streaks of brown and black. The gums recede and 

 waste away, and the tushes wear to stumps, and project directly 

 forward, and often one or both drop out. 



Irregularities of Teeth are by no means uncommon. 

 The practice of punching out the milk-teeth, to hasten growth 

 of permanent set, induces growth in a wrong direction, and, 

 not meeting the opposing tooth, they do not wear down regu- 

 larly. A horse occasionally has what is called a " pig jaw ;" that 

 is, the upper longer than the lower, in which case the teeth 

 grow to so great length as to interfere with taking food. 



Diseases of Teeth. Fortunately the horse is singularly 

 exempt from diseases of teeth common to man. The edges of 

 grinders sometimes wear unevenly, and the sharp edges cut the 

 cheek and cause ulcers. The cure is to rasp off the sharp edge 

 with a tooth-rasp. Many a horse has suffered from neglect of 



