IRREGULARITIES OF THE DENTAL APPARATUS. 765 



3d. At what age is the operation j^ractised f How many teeth are 

 extracted at one time f 



This varies. Sometimes the pincers alone are extracted towards 

 the end of the second year ; sometimes at a later period only the in- 

 termediates are extracted ; or, finally, at a still later period the corners 

 alone may be removed. But there are some horses in which the pincers, 

 the intermediates, and the corners are removed at successive periods. 

 It appears that the operation is sometimes performed only upon the 

 teeth of the upper jaw. 



In this respect there are no fixed procedures. The principle of the 

 stock-breeder who has colts to raise is to dispose of them at the earliest 

 possible moment to avoid the expense of feeding, the chances of loss 

 or of deterioration, or, finally, to realize in the shortest time the amount 

 which their sale will produce. 



This trick is practised at from three to three and one-half years of 

 age, if it be desired to sell the horse as a four-year-old, and from four 

 to four and one-half if he is to be represented as a five-year-old past. 

 It is understood, of course, that in the first case the four intermediates 

 are extracted ; in the latter case the four corners. 



4th. Does the extraction of the deciduous incisors hasten the eruption 

 of the adult teeth f 



Nearly all our colleagues have given an affirmative answer to this 

 question ; one alone claims that not only does it not hasten, but that 

 it even retards the eruption of the permanent teeth, according as it has 

 been practised six, eight, or ten months before the natural period of 

 their replacement. The others declare that the eruption is quick- 

 ened, if the operation has been properly performed ; that is to say, if 

 the whole of the milk-tooth has been removed. 



M. Yvon^ has, in this respect, communicated to us some interesting 

 observations. 



"This operation," says he, "hastens the evolution of the tooth 

 but little. In the vicinity of Bayeux, and especially in the district of 

 Caen, where extraction of the incisors of horses is frequently performed 

 to make the animals apparently older and to dispose of them more 

 promptly, it is practised only, at furthest, six months before the period 

 when the teeth would naturally fall out. More often, however, it is 

 * done two months and even only one month before this period, in order 

 to dispose of them more easily to the remounts or sell them to dealers. 

 In the first case the eruption of the permanent teeth is hastened two 



I Yvon, note commuuiqu^e. 



