VETERINARY DENTAL SURGERY. 245 



The corner incisors are all the temporary teeth 

 remaining at this time. At four to four and one- 

 half years they are replaced by permanent teeth. 



At the fifth year the anterior border of the cor- 

 ner incisors meet, the triangular space on the poster- 

 ior surface of these teeth yet remains and is very 

 characteristic of a five-year-old. The tables of the 

 lateral incisors are now fully formed, the central cav- 

 ity being surrounded by a line of worn surface. At 

 this age a horse is said to have a full mouth. 



If we carefully examine the above facts we can 

 see some reason for the oft repeated statement: "I 

 had rather work a three than a four-year-old horse, 

 for they can better stand the work." Between the 

 fourth and fifth years the dental changes are the cut- 

 ting of four permanent incisors, four canine and 

 eight molars making sixteen teeth which are all 

 growing at one time. Is it a wonder that the ani- 

 mal often suffers severely and is unable to take much 

 solid food? 



After the fifth year the age of the horse is deter- 

 mined by examining the cavities and general appear- 

 ance of the (lower) incisor teeth. 



At six years the cavities of the corner incisor teeth 

 are completely surrounded by a line of worn surface. 



The central incisors have their cavities partially 

 worn out. Their boundaries however are distinctly 

 marked by the central enamel with which it is sur- 



