CHAPTER XX 

 IRREGULARITIES OF THE TEETH 



Parrot-mouth, Lantern-jaw and Scissor-mouth. — The com- 

 mon deformities of the jaw and teeth are the overshot or parrot- 

 mouth, the undershot or lantern-jaw, and the scissor-mouth. 

 These different deformities result in unequal wear on the table 

 surfaces of the incisors and molars. In both the overshot and 

 undershot jaws, the incisor teeth become abnormally long. In 

 the parrot-mouth, the wear occurs on the posterior face of the 

 superior and the anterior face of the inferior incisors, the teeth 

 becoming worn to rather a sharp edge, depending on the degree 

 of the deformity. In the lantern-jaw, the wear occurs on the 

 posterior face of the lower and the anterior face of the superior 

 row of incisors, the teeth taking on somewhat the same shape as 

 the parrot-mouth. The greater the deformity and the older the 

 horse becomes, the more difficult it is for the animal to feed or 

 graze on pasture. 



In all horses, the two rows of molar teeth are wider apart in 

 the superior than in the inferior jaw. This results in the ex- 

 ternal border of the tables of the superior row of molars becoming 

 longer, or projecting further downward than the internal border. 

 The wear on the table surfaces of the inferior row of molars 

 is just the opposite of the superior row. In the scissor-mouth the 

 wear takes place largely on the internal face of the superior and 

 the external face of the inferior row of molars. The teeth be- 

 come worn to more or less of a blunt cutting edge, and after a 

 time the molars come together somewhat like the jaws of a 

 pair of scissors. A horse with a badly deformed scissor-mouth 

 is unable to grind the feed, and unless given special care, suffers 

 severely from innutrition. 

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