104 SOUNDNESS IN HOESES. 



appear younger on the near side than he really is, and 

 older on the off side. In such instances we should take 

 the mean of the ages shown. 



The incisors of some animals are abnormally long in 

 both jaws. In such cases, the teeth meet at an unusually 

 acute angle, and have a marked outward divergence. In 

 order to arrive at a close approximation of the age, which 

 is here somewhat difficult, we should imagine the teeth 

 to be cut down to their normal length. It would gener- 

 ally be judicious, on the part of the owner, to have this 

 actually done to such teeth. 



Although we see, as a rule, "parrot-mouth'^ only in old 

 horses, still it is common enough to observe, in five- or 

 six-year-old animals, that the upper front incisors project 

 a little beyond the lower ones, while the posterior edges 

 of the teeth are in juxtaposition. It is possible that 

 animals possessing this peculiarity become, finally, parrot- 

 mouthed with advancing age. In this aggravated con- 

 dition (see Fig. 26), the upper front incisors overlap their 

 fellows in the lower jaw, considerably more than do the 

 other teeth ; the upper corner ones, least of all. 



Surgical interference is almost always called for in 

 well-marked cases of parrot-mouth; as this condition 

 greatly affects the animal's power of grasping and cutting 

 his food. 



Abnormal wear of the teeth from crib-liting. — Many 

 horses, from irritability on being handled, though free 



