760 THE EXTERIOR OF THE HORSE. 



Here the abnormal wear is produced by the contact and friction of the 

 dental arcades upon the halter-strap by which the animal is fastened. The 

 latter stands back in the stall to stretch the halter-strap to its full length, cribs 

 upon the latter, and afterwards rubs his teeth over it alternately from above to 

 below and from before to behind. The convex form of the incisive arcades ren- 

 ders these movements at first difficult and uncertain ; but soon the strap strikes 

 more particularly the interstice of two teeth and enlarges it by reason of the 

 repeated friction. The vertical gutter, becoming more and more hollowed, ex- 

 tends to the posterior face. The result is that the gum becomes irritated, and 

 then, in order to avoid the pain which results, he cribs on the other side. Anal- 

 ogous phenomena taking place, he will then crib at another point of the arcade, 

 where a new gutter will soon be worn out, and so on. 



This abnormal wear usually takes place on both jaws, although it may some- 

 times affect only one, the superior or the inferior. In all cases, and although 

 the number of gutters may not be multiple, the dental tables scarcely furnish 

 any index of a nature to assist in the recognition of the age. It is necessary, 

 therefore, to depend upon the length, the direction, and the freshness of the 

 incisors, the characters of the tushes, those of the molars, and, finally, upon all 

 the external signs, which we will study presently. 



Such are the varieties of wear, as numerous as remarkable, wit- 

 nessed on the teeth of cribbing horses. 



A number of them may often be combined ; the teeth may be 

 bevelled off at the anterior border of their tables and at the same 

 time be very much shortened ; it is the same as regards the posterior 

 bevels. 



But what we have not observed yet is an abnormal wear of the 

 anterior and posterior borders upon the teeth of the same arcade, 

 either in the upper or lower jaw. In order that such wear may be 

 produced, the subject should be capable of changing his manner of 

 cribbing, that is to say, of correcting himself spontaneously of a bad 

 habit while he still has the power to indulge in it (which is almost 

 illusory) ; or, again, the animal should be in some manner forced into 

 this change by reason of his master altering the position of the sur- 

 rounding objects on which he previously practised this habit. But, in 

 such cases, it is more common to see cribbing cease altogether for a 

 variable period of time, only to reappear as soon as circumstances are 

 again favorable, rather than to observe a change in the horse's manner 

 of cribbing. The subject does his best to find other objects and to 

 overcome the restraint which is placed upon him, and he frequently 

 succeeds in this, but he will always crib in the same manner. Never- 

 theless, it is well known that the cribbing horse, prevented from 

 touching an external object, will, for this reason, not lose the habit, 

 because he will learn to crib in the air, become a wind-sucker. 



