DISEASE IN GENERAL 201 



constitution" when he is susceptible to the influence of his 

 surroundings. An individual may have much resistance against 

 many types of disease influences' and yet be weakly constituted 

 in some way. The strength of general constitution is measured 

 by the strength of the least resistive ability, like the strength of a 

 chain is that of its weakest link. Constitution is indicated by a 

 general healthy appearance and perfect respiration, digestion, 

 and circulation. 



Condition is the term used to denote the degree of bodily 

 health. When the animal is enjoying perfect health it is most 

 resistant to disease and is said to be in "good condition," that 

 is, at its highest point of efficiency for the performance of work. 

 Work in this connection signifies either actual labor, or the pro- 

 duction of milk, meat, or wool. Condition in working animals 

 is denoted by hard, firm muscles, a clear eye, and quick percep- 

 tion; in meat-producing animals by rotundity and fullness of 

 development of the body; in milk-producing animals by fine 

 quality and pliability of the skin. An animal is said to be in the 

 "pink of condition" when all the organs of the body are working 

 in harmony. The expression probably originated from the fact 

 that the visible mucous membranes of healthy animals are 

 always a delicate pink color. 



When one or more of the various causes of disease are at work 

 the animal is "out of condition" and incapable of performing 

 work in the most efficient manner. Under these detrimental 

 influences the natural powers of resistance are weakened and 

 the animal is more susceptible to disease. 



The previous pages in this chapter have dealt with some of the 

 causes of disease arid the natural means of resistance to disease. 

 Their study should show the student why an infection is fatal in 

 one animal, but may produce only a moderate sickness or cause no 

 damage whatever in another. Moreover, they have introduced 

 the subject of infection and immunity, that ever-waging contest 

 between the invading army of bacteria on the one side and the 

 defending army, consisting of the body defenses, on the other side. 



THE SYMPTOMS OF DISEASE 



Symptoms are the signs of impairment which occur as the 

 result of disease. They vary in intensity depending upon the 

 organ affected and extent of the disturbance. Only when an 



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