50 EQUINE PLEURO-PNEUMONIA 



§33. Etiology. There is some question concerning the 

 specific cause of this disease. A large number of suspected 

 microorganisms have been isolated and described, but the 

 streptococcus of Schiitz seems to be the only one with which 

 the disease has been produced experimentally. 



In 1887, Schiitz published the results of his investigations 

 into the cause of Brustseuche. He described an organism 

 which appeared as a diplococcus in tissues, but in bouillon 

 cultures it grew in flocculi. From the description, it appears 

 that this organism was a streptococcus, notwithstanding the 

 fact that in the tissues it appeared more often as a diplococcus. 

 In cultures, he speaks of it as chains growing in masses. He 

 mentions a capsule, but in the cases described it does not seem 

 to be invariably present and it is not mentioned in prepara- 

 tions made from cultures. Chantemesse and Delamotte, Gal- 

 tier and Violet, and Cadeac found streptococci in the lesions 

 of animals .suffering from this disease. Although differences 

 seem to exist in the streptococci isolated and studied by these 

 investigators, there is a striking similarity between them. It 

 is not at all unlikely that difference in methods may explain 

 the variations mentioned. 



According to Schiitz, cultures inoculated into horses pro- 

 duce the disease when injected directly into the lungs by 

 means of a hypodermic syringe. The resulting contagious 

 pleuro-pneumonia exhibits the same symptoms and runs a like 

 course to those observed in cases of the disease contracted in 

 the natural or common manner. The essential changes shown 

 on post-mortem examination were multiple gangrenous patches 

 in the lungs with parenchymatous degeneration of the most 

 important organs. The inoculated streptococci were found in 

 the tissues of the artificially produced disease. According to 

 Schiitz, the bacteria of contagious pleuro-pneumonia are found 

 most numerously in the lungs or the exudate on the pleurae. 

 They are also met with in the nasal discharge and in expired 

 air (Rust). Nothing positive is known concerning the life 

 history of the streptococci outside the animal body. They are 

 supposed not to be able to live longer than six weeks within 



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