176 THE DOG IN HEALTH. 



dicated in the following tabular comparison with the den- 

 tition of man : 



Dog 

 Man. 



The usual order of eruption is : Fourth, above ; fifth, 

 above ; fifth, below, soon followed by the sixth and sev- 

 enth ; three anterior above ; about a week later the three 

 anterior are replaced below. The four first molars on 

 each side are often termed premolars. 



From the nature of the case, it is impossible to deter- 

 mine the age of a dog by his teeth after the permanent set 

 is complete, as their condition varies greatly with the sort 

 of wear to which they are subjected, this depending on 

 the food, etc. 



In a perfectly healthy dog the teeth remain white 

 for several years ; but if there be abnormalities of the di- 

 gestive juices, the teeth are apt to become discolored by 

 tartar, an accumulation of lime-salts, entangling foreign 

 matters. 



It is well to give a dog, therefore, suitable bones, hard 

 biscuits, crusts of bread, etc., to clean the teeth. 



Dogs of most breeds are at their best physically in 

 their third year, though some individuals of these, and 

 many in the larger varieties, continue to improve up to the 

 fourth year. 



After the sixth year a dog usually shows signs of fail- 

 ure ; after the eighth he is old, and after the tenth year he 

 is, as a rule, unfit to propagate his kind or engage in those 



