INTEODTJCTION. 31 



only should be used. Thus, if a horse have a com or 

 bruised heel, he will be as sure to go lame as he would 

 with an ordinary sprain. The difference is, that he not 

 only stretches out the sore foot, but he elevates the heel 

 from the ground, and will not set his foot flat to please, or 

 it may be said to deceive any one. The uneasy eye, the 

 anxious expression, and the sharp, peculiar look, tell the 

 tale of suffering, and bear testimony to a description so 

 faithful and true, that every man should understand how 

 to interpret them. 



THE PEINOIPLES OF DISEASE. 



Congestion. — By this term is meant an undue flow of 

 blood into a part, and remaining in it. The blood-vessels 

 lose the power of contracting and emptying themselves, as 

 when in health. Congestion is not accompanied with in- 

 flammation, as some suppose, and may exist without irrita- 

 tion. Irritation is only present when the blood passes more 

 rapidly into a part than its vessels can carry it out, and 

 inflammation only is present when more fluid is thrown 

 into the vessels than they can get rid of 



Irritation. — ^This peculiar condition is the result of in- 

 •«*eased sensitiveness, or an exalted action, accompaniea 

 with quickened beating of the heart and pulse. When we 

 apply the term to special cases, it will be better under- 

 stood, as irritation of the bowels producing diarrhoea, of 

 the bladder frequently passing off urine, of the eye causing 

 an increased flow of tears, and of the throat giving rise to 

 cough. 



Inflammation differs from irritation, inasmuch as it is 

 more painful. There are three varieties — acute, sub-acute, 

 and chronic. Inflammation has also three terminations : 



