IRREGULARITIES OF THE DENTAL APPARATUS. 



759 



would be interesting and useful to prove by observation whether horses which, 

 without being very aged, have the incisor teeth very short may not have aban- 

 doned the habit of cribbing. M. Zundel l has related some facts confirming the 

 opinion ; we ourselves also know of several examples of this nature. 



Horses which crib in this manner seize the foreign body with the whole 

 extent of their dental table, most ordinarily the plane surfaces, external or 

 internal, of a manger whose free border is too thick to be lodged betweerFthe two 

 arcades at the moment of the effort. There is then a regular but excessive wear 

 over the whole surface of friction of the teeth which bear against the foreign 

 body. 



The pincers and intermediates are nearly always the seat of the diminution 

 of length. This fact is quite evident when the jaws are closed, for there exists 

 a more or less wide interval between these incisors, the corners having preserved 

 their normal length and contact. 



At other times, the shortening may affect all the teeth of the same arcade, 

 and then it may, even if perceived, at least fail to be attributed to cribbing, if 

 we are ignorant of the relations of cause and effect which connect this variety 

 of wear with the vicious habit as to the character of which we may be consulted. 



The following are the three possible cases which we have noticed: 



a. The shortening affects only the teeth of the superior jaw (B), 



b. It affects only those of the inferior jaw (C). 



c. Finally, it is seen on both jaws simultaneously (D). 



In the last example the free border of the manger is narrow enough for the 

 animal to be able to grasp it easily between the teeth. 



5th. The Abnormal "Wear takes Place on the Lateral or Adjoin- 

 ing Faces of the Incisors (Fig. 329). The varieties of this category are very 

 numerous and remarkably complicate the determination of the age. All are, 



FIG. 329. Abnormal wear produced by cribbing. 



however, characterized by the formation of a double bevel at the expense of the 

 lateral or contiguous faces of the teeth, converging towards the centre of the 

 mouth. There results from this upon the anterior face of the incisive arcades, 

 and when the jaws are closed, a series of vertical gutters or grooves whose bot- 

 tom occupies the interstice comprised between two adjacent teeth. The tables 

 at these places are deeply notched upon their anterior and lateral borders, by 

 reason of the situation and the mode of convergence of the bevels. 



1 Zundel, Dictionnaire de medecine, de chirurgie et d'hygiene ve'terinaires, t. iii. p. 585. 



