2 AGE OF THE DOMESTIC ANIMALS. 



apparatuses, and it is capable of its best and greatest work; 

 in this stao-e there is an equiUbrium estabUshed between the 

 waste and Repair, and the activity of composition is equal to 

 that of decomposition. Third, senility, or old age, the period of 

 deterioration; during this period the animal may have the 

 strength of previous years, it may be capable of as great efforts, 

 and h-om experience may even display greater intelligence ; for 

 specific purposes the animal may at this time be capable of ren- 

 dering even greater service than it could have given when 

 younger, but its eiforts now demand a waste of tissues no longer 

 capable of rapid repair, and continual drains on its organs alter 

 them in size and depreciate them in function, and the whole 

 animal economy undergoes a steady deterioration in usefulness 



and value. 



These periods may be called that of growth, the stationary 



period, and that of decline. 



The veterinarian is the expert referee in all questions of 

 age, and any addition to our knowledge in regard to it needs 



no apology. 



If animals lived a perfectly equable hfe, the changes whicli 

 take place in their form and character would be regular and 

 easy to appreciate; but, from overwork, from the alterations 

 produced by excessive food, want of food, or irritant substances; 

 from the effects of variable surroundings, at times trying on the 

 constitution, at other times rendering the external tissues deli- 

 cate and sensitive to exposure, the wear and tear on them is 

 irregular. Excessive work in one animal and want of food in 

 another open easy avenues for the ravages of time, which would 

 not show on one which was better nourished and better cared 

 for. The well-bred colt training over fast miles from a yearling, 

 and the great draught-horse hauling a load of several tons in 

 our large cities, demand excess of food for their herculean tasks. 

 The greater quantity of food overtaxes the organs in proportion, 

 and, in the same number of years, one animal may hve double 

 that of another in usefulness and functional activity. 



