Diagnosis. Prognosis. 173 



of other patliologic processes deserve full consideration in es- 

 tablishing the particular nature of existing- pleurisy, which may 

 depend upon a lourulent inHamniation of neigh))oring or more 

 distant organs ; purulent or ichorous pleurisy sometimes occurs 

 after penetrating wounds of the thorax. Pleurisy accompanying 

 chronic affections of the lungs (tuberculosis, glanders, actinomy- 

 cosis, hmgworm disease) is usually filirinous or serofibrinous. 

 In tuberculosis and in cachectic processes in general it may 

 also be hemorrhagic. Assistance in the diagnosis may be af- 

 forded in cattle and also in dogs by a tuberculin test. The char- 

 acter of the exudate is best ascertained by an exploratory punc- 

 ture, which is perfectly void of danger and which should be 

 performed in all doubtful cases. 



^-^C 



Fig. 29. Sediment of an exudate in serofibrinous pleurisy of a horse, a, polynuclear 

 leucocytes ; h, red blood-corpuscles ; c, endothelial cells in a condition of fatty degen- 

 eration. 



The exploratory puncture is best made with a hypodermic syringe; its needle 

 is pushed into the area of dullness, into the pleural cavity, best in the sixth or 

 seventh intercostal spaces. In withdrawing the piston of the syringe, fluid often 

 enters even if the needle has been pushed into masses of fibrin. The end of the 

 needle may touch the lung and in this manner we may eventually gain some informa- 

 tion about the consistency of the lungs; if the needle has been pushed into the 

 lung parenchyma, we get pure blood or, in the presence of pneumonia, a bloody 

 stained fluid. The fluid obtained by puncture may be used for bacterioscopic 

 examination and for animal inoculation. 



The prognosis depends upon the etiologic factors, the char- 

 acter of the exudate, the species and the age of the animals 

 affected. Pure fibrinous pleurisy following croupous pneumonia, 

 is not of very grave significance, but the accumulation of a fluid 

 exudate under these and other circumstances is usually an un- 



