262 



PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



appears through the gum also at six months. The corner incisors are 

 displaced and permanent ones cut at nine months. The permanent tusks 

 are also cut at this period, as well as the fifth molar on either side of 

 each jaw. At one year the middle incisors are changed and the tusks 

 appear of considerable size. The deciduous molars are likewise shed at 

 one year and succeeded by permanent. At eighteen months the denti- 

 tion of the pig is completed by the cutting of the lateral incisors and the 

 last or sixth molar. The succession of teeth in the pig is shown in the 

 following table : 



Other Signs of Age in Domestic Animals. In horned animals the 

 horns grow annually a certain length, and this is shown by the appear- 

 ance of an extra ring every year at the root of the horn. .For the first 

 two years the rings are so indistinct that, in calculating the age in an 

 animal five or six years old, the first ring indicates a three-years' growth, 

 so that an animal with six rings must be regarded as eight years old. 



Fraud may be practiced to destroy the marks of age. Angularity of 

 form, sharpness of bones and gray hair are not easily disguised, but teeth 

 can be filed and marked and horns scraped. Making false marks on teeth 

 is called " bishoping." Gray hairs may be painted, called "gypping." 

 In old horses the remarkable depressions behind the orbits are some- 

 times pricked and blown up with air; this is called "puffing the glym." 



Some of the abnormal conditions of the teeth are the persistence of 

 temporary teeth, so that twelve incisors may be present in the lower jaw, 

 or the permanent teeth may fail to develop. One or more teeth may be 

 absent, from removal or from faulty development. 



In the following table the order of dentition of the domestic animals 

 is recapitulated : 



