MORBID PHENOMENA. 25 



are again divided into the active or dynamical, wlieii they are 

 only discoverable by motion or manipulation, and the passive or 

 statical, when they are obvious without such action; ])ositive, 

 when they consist of phenomena actually present, and negative, 

 when they consist in the absence of phenomena. Diagnostic 

 symptoms are those symptoms which point out the distinction 

 of one disease from another, and the art of diagnosis is that by 

 which the practitioner is enabled to arrange symptoms into signs 

 of disease. A symptom or a set of symptoms which are peculiar 

 to any particular disease, are said to furnish pathognomonic signs 

 of such disease, and are called pathognomonic or pathognostic. 

 A simple symptom is rarely pathognomonic, but two or three 

 conjointly often are so. For example, a discharge is seen to 

 issue from a horse's nose. This is a symptom. It may, however, 

 be due to a catarrhal inflammation, to disease of the teeth, or 

 of the bones of the face ; to an affection of the lungs, to a col- 

 lection of pus in the guttural pouches or facial sinuses, or to 

 glanders. The discharge is so far a sign, that it indicates the 

 formation of pus. If we discover, on examination, that the dis- 

 charge is associated with ulceration of the Schneiderian membrane, 

 with enlargement of the submaxillary lymphatic glands, and more 

 especially if the discharge itself is of a glutinous consistence 

 and starchy appearance, we conclude that it is due to glanders. 

 Taken collectively, these symptoms constitute a diagnostic sign. 

 of glanders, and are said to form the pathognomonic symptoms. 



The interpretation of symptoms requires the closest observa- 

 tion, and in many instances repeated examinations of the 

 patient ; for the veterinarian is never assisted by what are 

 termed in human medical practice the subjective signs of disease, 

 namely, the sensations felt and described by the patient himself. 

 In veterinary practice all signs and symptoms are objective, 

 and each sign or group of signs has to be duly considered, 

 compared one with another, and each with all ; so that a close 

 observation is essentially necessary before a due and proper 

 conclusion can be arrived at and an opinion pronounced. It is 

 by comparing at intervals the various modifications and altera- 

 tions which occur in the signs and symptoms of disease, that we 

 are enabled to p)rog7iosticate the nature of its termination, or, in 

 other words, to make our prognosis. 



