422 Types and Market Classes of Live Stock 



are not fully in wear. At two years, all of the temporary teeth are in 

 wear, kt 2}^ to 3 years, the middle pair above and below are shed, 

 and are replaced by permanent incisors. These are broader, heavier 

 teeth, and have a rather rough or corrugated surface, whereas the sur- 

 face of the milk teeth is smooth. At 53^ /o ^ years, the intermediate 

 pair of permanent incisors appears in each jaw. At -4H ^o 5 years, the 

 comer pair of milk teeth above and below are displaced by permanents, 

 and the horse may be said to have reached maturity. 



After five years the age is not so easily determined, nor are the 

 indications so accurate. We rely mostly upon changes in appearance 

 shown by the wearing surfaces of the teeth to tell us the age beyond 

 five years. The wearing surface of new permanent teeth has a long, 

 narrow cup or depression running across it transversely. The rims 

 of these cups disappear through wear, leaving two distinct rings of 

 enamel, one around the margin of the tooth, and the other around the 

 cup. With wear, the cup becomes smaller, more oval or rounding in 

 shape, and more shallow, until it is finally worn almost completely 

 away. Continued wear exposes the tip of the pulp canal or cavity in 

 the center of the tooth, and the exposed tip of this canal appears be- 

 tween what is left of the cup and the front of the tooth. The exposed 

 pulp cavity is called the "dental star." 



At six years, the middle pair in the lower jaw are usually worn 

 level and the wearing surface tends to become oval in form. The 

 central ring of enamel is plainly evident, but is smaller than at five 

 years, indicating considerable wear. The lower corner teeth, which 

 at five years showed little or no wear, now usually show wear, the edge 

 surrounding the cup being much less sharp and shell-like. The canine 

 teeth, which first appeared at four years are now completely out. At 

 seven years, the lower intermediates are also levelled on the wearing 

 surface and the ring of central enamel becomes wider from before back- 

 ward, and shorter from side to side. A hook or "swallow tail" is often 

 present on the upper corner teeth because they are broader than the 

 lower corners and do not wear down evenly. At eight years, all the 

 lower teeth are levelled and the dental star appears upon the center 

 and intermediate pairs, showing between the front border of the tooth 

 and the front border of the central enamel. 



At nine years, the hook or swallow tail on the upper corners has 

 often disappeared. The lower centers are round; their central enamel 

 has a triangular form; and their dental star is narrower and more dis- 

 tinct. The center pair of the upper jaw are usually levelled. At ten 

 years, the changes previously mentioned become more marked, and 

 the upper intermediates are usually levelled. At eleven years, the 

 central enamel of the upper corner teeth becomes elliptical and tends 



