AOES OF SHEEP, PIGS, AND HORSES 



339 



As age advances, the teeth grow narrower and slimmer until advanced 

 age, eight or nine years, when they often shorten rapidly from wear, 

 and finally disappear. So long as the teeth remain strong and fairly 

 firm, the sheep may be said to be in good working condition. 



Swine. 



While swine have two sets of teeth, temporary and permanent, 

 as in the other domestic animals, the dentition is so irregular as to be 

 of little service in determining the age of the animal. Moreover, the dif- 

 ficulty of catching, holding, and examining the animal is so great that 

 the teeth are seldom, if ever, used to determine the age of swine. In 

 market stock, the age does not play an important part, as the value 

 depends entirely on the weight and condition of the animal, except in 

 the case of old sows and stags (castrated mature males). The former 

 are easily distinguished by evidence of having suckled pigs, and the 

 latter by the tusks and the development of the ''shield " — a coarse 

 heavy fold of muscle under the skin on the shoulder. In breeding 

 animals, the age is always indicated on the certificate of registry of 

 pure-bred stock. 



Horse's teeth at different ages (Roberts). 



The lower nippers at two 

 years old. 



Lower nippers at three 

 years of age. 



/ 



Side view of the 

 teeth of a four- 

 year-old. 



