40 DISEASE. 



present ; and we have to regulate our remedial measures by 

 what has or has not been done before we were called in : 

 indeed, it oftentimes dispels a cloud of mystery; frequently 

 becomes absolutely necessary towards the future treatment 

 of the case. 



By the cause of a disease is to be understood, anything 

 that may give rise to the ailment. By etiology is meant 

 the study or doctrine of causes. 



The Causes of Disease comprehend a variety of circum- 

 stances tending to its production. When we come to coa- 

 sider the number and nature of the functions ; the delicacy 

 of the structures ; and take into our account the chances to 

 which the animal is every day exposed ; we can only wonder, 

 while the causes appear so numerous, that disease is com- 

 paratively so rare. In a state of domestication, the horse is 

 surrounded on all sides by the incentives to disease : he 

 harbours them within his own body, and they are inflicted on 

 him by man. Numerous as they are, however, these causes 

 admit of classification under two heads : — they are either 

 predisposing or exciting. Some add a third class, and call 

 them proximate. 



Occasional causes are such as excite disease to which 

 there is a predisposition. Determining causes are such as 

 give rise to disease. Specific are such as produce always 

 the same disease or effect. (Delafond.) 



These divisions should be confined to such complaints 

 as by their slow operation modify the organization and 

 change the structure of parts, giving them an aptitude to 

 display the different phases of disease. 



Predisposing causes are either general or local : the former 

 influencing numbers, the latter but one animal. The general 

 predisposing causes are — 1. The air animals breathe. 2. The 

 food they eat. 3. The drink they imbibe. 4. The places 

 they inhabit. 5. The work they perform. 



Predisposing Causes are those which render the body 

 susceptible to exhibit disease. In their nature, they may 

 either be inmate or acquired : i. e., an animal may be born 

 with a predisposition to some particular diseases ; or he may 



