56 EQUINE PLEURO-PNEUMONIA 



and sometimes even ulcerated. The bronchial mucous mem- 

 brane is swollen and inflamed. 



In other cases, the lesions are those of lobar pneumonia, 

 in which the stages of hyperemia, red hepatization, gray hepa- 

 tization and resolution ^in favorable cases) follow each other 

 in regular order. In a fatal case post-mortemed by the writer 

 the right lung was entirely involved, the left one being but 

 slightly hyperemic. In non-fatal cases, the crisis is reached 

 on the 5th or 6th day, after which resolution begins. 



As alread}' stated the lesions in this disease are so ex- 

 ceedingly variable that, in addition to the more typical pneu- 

 monia, almost any modification can be found. The detailed 

 description of many of these variations as described by Dieck- 

 erhoff are worthy of careful study. 



The duration of the disease is from two to three weeks. If 

 there are complications the course may be much longer. 



The mortality is often very high. The literature shows it 

 to vary from one to thirty per cent. It frequently leaves ani- 

 mals practically worthless because of pleural adhesions and 

 other complications. 



Jj 36. Differential Diagnosis. This disease is to be 

 differentiated from several disorders. 



1. Influenza. In the general form, where the localiza- 

 tion of the lesions in the lungs does not occur, it is often con- 

 fused with influenza. 



2. Bronchial pneumonia. The pneumonia which often 

 follows colds must be differentiated from the epizootic form. 



3. Aspiration pneumonia. The pneumonia following the 

 introduction of foreign substances into the lungs, as often 

 happens in giving medicines, must be distinguished. The 

 history, course of the disease, and the spread to other animals 

 will do much to settle the diagnosis. In case of post-mortem, 

 streptococci are often found in all the pneumonias. We have 

 no positive lesion or organism bj' which to determine the 

 diagnosis. 



§ 37. Prevention. The short period of incubation and 



