98 THE ARMY HOBSE IN ACCIDENT AND DISEASE. 



consequence are finding a greater grinding surface on the lower ones. 

 In some cases the dental star may now be detected between the 

 enamel island and the front border of the tooth in the central in- 

 cisors. It appears in the form of a yellowish transverse line. 



After the age of 6 wear alone, by changing the form and appear- 

 ance of the table surfaces and the angle at which the uppers and 

 lowers meet, furnishes the indications of age ; and as the wear varies 

 with the hardness of the teeth and the character of the food, it is at 

 once apparent that no two cases will be exactly the same. Hence, 

 after the animal is 8 years old the age indications have become un- 

 reliable. From now on with the passing of each year they become 

 less and less reliable. After the twelfth year there is but little prob- 

 ability of judging the age accurately. 



On an average it is found that the cups of the upper incisors are 

 worn out in the centrals at the age of 10. 



At 15 in most cases the enamel island has disappeared from the 

 lowers, and the dental star has become distinct and round in the 

 center of the tables. The enamel island persists in the uppers usually 

 until the animal is about 18. 



After 20 the horse is considered to have reached the limit of his 

 life. The characters then presented by the teeth are those of extreme 

 age. The table surfaces are elongated from front to rear. Some- 

 times the crowns are very long and extend almost in prolongation of 

 the jaws. Sometimes they are Very short and are worn down to a 

 level with the gums. The crowns now appear to converge toward 

 the median line, whereas in youth they appeared straight or slightly 

 divergent. 



Many deceptions may be practiced or many conditions may exist 

 which render the determination of the age very difficult. Some dis- 

 honest dealers and breeders resort to pulling the milk teeth a few 

 months before they would fall, thereby hastening the appearance of 

 the permanent ones and giving the mouth an older appearance. 

 Sometimes the notches in the upper comers are rasped away to make 

 the 7-year-old mouth look younger. " Bishoping" is another form 

 of deception that is sometimes practiced. This is done to make an 

 old mouth appear young. New cups are drilled in the old teeth, and 

 these cups are then stained black by some artificial means. This 

 practice, however, should never deceive the close observer because 

 the ring of enamel, which is always present around the natural cup, 

 can not be reproduced in the bishoped mouth. Moreover the teeth 

 will show by the angle at which they meet and by the form of their 

 table surfaces that the mouth is too old for cups to be present. 



Horses with parrot or overshot mouths, and horses in the habit of 

 cribbing, subject their teeth to unnatural wear, which renders the 

 determination of their age very difficult. 



