ESTIMATING THE AGE BY THEIR TEETH 51 



differences that exist. It is to be remembered however, that 

 the foods fed them have a marked influence on the wear of 

 the teeth, thus making differences which are not solely due 

 to age. Liberal feeding which favors early maturity is also 

 likely to affect the appearance and arrival of the incisors. 



86. Appearance of Incisors. The difference in the appear- 

 ance of the milk teeth or temporary incisors and the perma- 

 nent incisors is readily understood after they have been once 

 inspected. The temporary incisors are slender, narrow and 

 constricted at the neck and very white, while the permanent 

 incisors are broader, thicker and usually of a light yellow- 

 ish tinge. 



87. Order of Appearance of Incisors. The permanent 

 incisors of both the upper and the lower jaws appear at the 

 same time so that it is only necessary to refer to the upper. 

 There are six permanent incisors in each jaw in the full mouth 

 and these make their appearance in pairs about as follows : 

 The pair in the center are the first to appear and they have 

 displaced the temporary pair and are full grown when the colt 

 is from 2j^ to 3 years old. The second pair or the two next 

 to these are fully grown at 3^ to 4 years and the third pair 

 have displaced the two corner temporary incisors at 4^ to 5 

 years of age. At this time the horse usually has a full mouth. 



88. Disappearance of the Tables. The best indications 

 of the age from five to ten years is the order of the disap- 

 pearance of the tables or marks in the incisors. At five 

 years the tables in the central pair of incisors of the lower 

 jaw show some wear but it is not until the horse is about six 

 years old that they have almost disappeared. At seven 

 years of age the * ' swallow-tail " as it is called, or the nick 

 in the corner incisor appears. At this age also, the two 

 incisors next to the central pair lose almost all traces of their 

 tables through wear, and at eight years the corner incisors or 

 outside pair are so worn as to be almost free from any ap- 

 pearance of having tables. At nine years of age the tables 



