96 THE ARMY HORSE IN ACCIDENT AND DISEASE. 



crown to its root, it is at once apparent that wear will continually 

 change the form of its table surface. 



In the young mouth the tables of the incisors are elongatetl from 

 side to side, while in the old mouth they are elongated from front to 

 rear. The intermediate forms through which they successively pass 

 are oval, round, and triangular. Roughly speaking, the incisors are 

 oval from 7 till 9 (centrals at 7, laterals at 8, and comers at 9), round 

 from 10 till 13, triangular from 14 till 17, and elongated from front 

 to rear at 18 or 19. 



In the young animal, while the teeth are still unworn to any extent, 

 the upper and lower incisors meet in such a way that they appear 

 as an evenly rounded arch. This arch, however, gradually changes 

 as the teeth wear away, until in age it has become very angular or 

 pointed. 



In examining the mouth of the horse to determine his age, three 

 features of the incisor teeth are studied: First, the angle at which 

 the uppers and lowers meet; second, the character and color of their 

 crown faces, and, third, the shape and appearance of the tables. 



To obtain the best view of the mouth, grasp the upper lip firmly 

 with the right hand, and place the left in the interdental space from 

 the right side, using the thumb to depress the lower lip, and the 

 back of the hand to press the tongue upward and backward. In 

 this way the right hand serves as a twitch to hold the horse, while 

 the left one uncovers the lower incisors. 



As has already been stated, the temporary teeth are all up and in 

 wear at about the age of 1 1 months. Between the ages of 1 and 2 

 the incisors remain the same in their arrangement, but begin to show 

 the effects of wear. 



At 2 the mouth presents veiy much the same appearance as it does 

 at 5, the difference being that the incisors are temporai'y in the fonner 

 and permanent in the latter, and that the 2-year-old has but Jive 

 molars on the side of each jaw, while the 5-year-old has all six. This 

 is the only case in which the molars might render assistance in the 

 determination of the age. At about the age of 2^ years the tem- 

 porary centrals are pushed out by permanent ones. The uppers are 

 usually shed a few weeks before the lowers. After these teeth make 

 their appearance, and until they are up and in wear, the horse is 

 rising, that is approaching, 3. 



At 3 the colt has two permanent incisors (the centrals) and four 

 teniporaiy ones (the laterals and corners) in each jaw. The centrals 

 are up and in wear ; that is, they are on a level w^th the temporary 

 teeth. The permanent centrals are seen to be darker or more yel- 

 lowish in color than their neighbors, and to have a well-marked 

 groove down their front face. Another important observation to 

 jnake is the appearance of the cups. In either the temporary or the 



