DENTAL INDICATIONS OF AGE OF A HORSE JQj 



have become obliterated in the lower jaw, traces of 

 them exist in the upper jaw. This is in consequence 

 of the enamel which occupies the pit in the centre 

 of the tooth not being elevated to a level with the 

 general surface, so that there is a greater depth to 

 be worn down in order to rub it off; and besides, 

 the upper incisors are less liable to friction and 

 wear than those of the under jaw, in consequence 

 of the lower jaw alone being moved in the act of 

 chewing, and the upper jaw being fixed and without 

 motion : its office is only to resist the pressure of 

 the under jaw in eating. 



The tushes are of no use whatever in enabling 

 us to determine the age of a horse, because the 

 change of their form is very uncertain. They do 

 not rub against each other like the teeth, and are 

 consequently less liable to be worn down. 



At nine years the infundibulum is gone in the 

 inferior incisors, and the inside and outside walls of 

 the upper corner teeth are level. 



At ten years the upper central incisors loose 

 mark ; at eleven years the middle, and at twelve 

 years the corner. To tell the age of the animal 

 beyond this period is difficult and uncertain, but 

 the shape of the teeth and other conditions facilitate 

 the undertaking. Young permanent teeth are about 

 twice as broad as thick, whereas the old are the 

 reverse, and this difference graduates itself yearly, 

 but not by growth and change in the teeth them- 

 selves. This change is by wear of the crown and 

 body of the teeth, and absorption of the alveoli or 

 sockets. In the young the teeth describe a semi- 

 circle, and stand perpendicular, and the alveoli or 

 sockets are deep. In the old they shoot almost 

 straight out, like the point of scissors, the upper 



