HISTORY AND CAUSES OF DISEASE. 39 



Pain is a symptom of most diseases ; one that originates 

 in impression upon the nerves distributed over the body. 

 Speechless as the horse is, yet it is possessed of many ways 

 to make its wants understood in health ; so under disease 

 does it point out the seat of its sufferings with a sagacity 

 hardly to be credited by persons who are strangers to its 

 habits. The drooping eye, in several chronic disorders ; the 

 looking back at the flank, in pneumonia ; the vividness of 

 the glance, in colic, together with the frenzied roll of it in 

 delirium ; are so many examples not to be misinterpreted by 

 the practitioner. Thus, we may apply to horses what Sir 

 Thomas Brown has said of men i — " In long observation w^e 

 may acquire a physiognomical intuitive knowledge; judge 

 of the interiors by the outside ; and raise conjectures at 

 first sight.-*^ 



A Division of Symptoms is into primary and secondary : 

 the former being those which first arise, and owe their 

 existence to the organ diseased ; the latter are such as owe 

 their production to the sympathy of other parts. Almost 

 all diseases present us with these two sets of symptoms : so 

 prone is the system to sympathise when disease is esta- 

 blished. 



Another Division of Symptoms is into local and general. 

 It is one, however, that hardly differs from the former. 

 Local symptoms are such as belong to the part primarily 

 disordered ; general, such as are indicative of the disturbance 

 of the system. 



Pathognomonic Symptoms are those which point directly 

 to the seat and nature of the disease. 



Diagnostic Symptoms are those that serve to distinguish 

 one disease from another that may resemble it. 



HISTORY AND CAUSES OF DISEASE. 



The History of a Disease comprehends whatever may 

 throw light on its origin. In veterinary practice, the his- 

 tory is of much importance. We have two objects in seek- 

 ing for it. We have to frame our theory of the disease 



