80 ANIMAL DENTISTRY. 



what prominent neck and are separated with gums shaped as 

 an inverted cone. The crowns do not contact one another 

 throughout their entire length, as in the horse five and a 

 half to six years old, for which the two-year-old might be 

 mistaken. The absence of canines (in the male) will also 

 assist in making the differentiation. The confusion is most 

 likely to occur in the examination of a thoroughbred or trot- 

 ter with a well developed muscular system, and the habits of 

 an older horse from training. 



FROM TWO AND A HALF TO FIVE YEARS. 



The determination of age during this period is more 

 simple and more certain than at any other period of the 

 horse's life, owing to the three successive prominent events 

 occurring during this period. At two and a half years the 

 central temporary incisors are readily recognized by being 

 loose preparatory to shedding. At three years old they are 

 cast ofJ and the permanent successors, broad and shiny, are 

 seen protruding beneath, leaving an interrupted surface in 

 the arcade. At three and a half to four years the laterals 

 undergo the same transformation, and at four and a half to 

 five, the corners. The five-year-old mouth is recognized by 

 the deep, oblong infundibula of the centrals and laterals 

 and the undeveloped condition of the corners. The latter 

 are bluish-white, have a short crown and do not contact their 

 opponents. The posterior edge of the table is still buried 

 within the gums. The canines are already visible in both 

 the jaws, but especially in the inferior, and the molar arcades 

 are completed. At two and a half years the first and sec- 

 ond molars cast ofif the temporary shells, at three the third 

 molar casts ofif its predecessor, and at four to four and a 

 half the sixth molar erupts, leaving at the end of this period 

 a full mouth of permanent teeth. 



