14 THEORY AND PRACTICE 



5. Diagnosis — Recognition of the disease. 



6. Prognosis — Probable termination. 



7. Morbid Anatomy — Structural changes 



produced by the disease. 



8. Hygiene — Prevention of disease by 



good management. 



9. Therapeutics — Medicinal indications. 



Etiology. — The causes of disease are divided into two classes, 

 predisposing and exciting. The predisposing arise within the 

 body. — they are intrinsic. Conformation and heredity are 

 examples. Consider a case of purpura hemorrhagica, a specific 

 disease due to the action of some microbe on the red blood 

 corpuscles. This germ lives especially in dirty stables, but is 

 resisted by animals in good health ; let the animals become 

 debilitated, however, and microbian invasion occurs. The 

 debilitation may be caused by a decayed tooth, by poor digestion, 

 etc., and we call these predisposing causes. A narrow chest and 

 straight ribs predispose an animal to chest diseases ; a sickle 

 hock to curb ; a straight hock to bone spavin. 



The exciting causes of disease in the horse are : — 



1. Overwork or too little work. 



2. Exposure to extreme changes of tem- 

 perature and to other meteorological 

 conditions. . 



3. Indigestible and impure food. 



4. Poisons, foul drinking water and con- 



tagions. 



Symptomatology. — The symptoms of disease are the signs, 

 changes, actions, inclinations, and feelings expressed by the ani- 

 mal. It covers everything that can be noticed as differing from 

 the normal. In order for a practitioner to be able to recognize 

 these, he must first be familiar with the normal habits of the 

 various species of animals. For everything differing from the 

 normal is a symptom of disease. 



Pathogeny. — The generation of disease relates to its minute 

 cause, for example a bacterium : the production indicates how 

 the disease is produced by the cause ; the development is the 



