556 NERVOUS DISEASES. 



" air-swallowing with support," and the latter, " air-swallowing with- 

 out support." 



METHODS OF PEACTISING THE VICE.— The cribber selects 

 his object of support at such a height from the ground that, while 

 using it and while standing up, he will be able to draw in his 

 chin towards his breast and arch his neck. The supporting object 

 will therefore never be on the level of the ground or placed high 

 up ; for to reach it in either of these positions, he would have to 

 stretch out his head and neck. I have never heard of a case of 

 a horse cribbing or windsucking while lying down. The cribber, 

 when tied up in a stall, will generally utilise for the practice of his 

 vice, the edge of the manger or rack-chain ; as these are usually 

 the most convenient objects within reach. Horses have been known 

 to crib on one of their forelegs. The cribber shov/s little or no 

 preference, however, in the stable or out of it, so long as the 

 selected object serves his purpose. As a rule, he seizes his point 

 of support with his front teeth, which consequently become worn, 

 chiefly, as follows : — 



1. By the front (and in exceptional cases, the rear) edges of 

 the teeth becoming more or less irregularly bevelled (Figs. 147, 

 U8 and 149). 



2. By the teeth becoming shortened. We may here recognise 

 the effect of the wearing-down process, by taking a front view 

 of the teeth (Fig. 150). 



3. By the teeth becoming bevelled and shortened. 



In the foregoing cases, the wear is almost always confined to 

 the front and middle incisors (nippers). We can see that in Fig. 

 148, three of the comer incisors were also implicated. 



4. Goubaux and Barrier state that the cribber, in the practice 

 of his vice, may effect vertical grooving between the incisors by 

 friction against the rack-chain, and that, when such an animal 

 wears a groove between one pair of incisors, so deep as to hurt 

 his gum, or to reach the sensitive portion of the teeth, he will try 

 another pair of incisors ; and so on. 



All these forms of wear, more or less complicate the determina- 

 tion of age by the teeth. 



Many horses, though free from the vice of crib-biting, wear their 

 teeth in a manner somewhat like that of cribbers, on account of 

 biting at their manger, etc., from irritability, when being groomed, 

 and sometimes from idleness. Here the question as to the animal 

 being a cribber, will be determined by the absence or presence, on 

 his part, of any attempt to swallow air. 



Cribbing, "however, is not always characterised by wear of the 

 teeth. The support may be taken by the lips, chin, lower edges 



