J74 • Intiiicnza ol Horses. 



in which the exudate contains streptococci in great numbers 

 in addition to the bipolar bacilli. 



The bipolar bacilli may sometimes be demonstrated in the 

 blood at the beginning of the febrile stage, they are very fre- 

 quently found in the liepatized tissue of the affected lungs, and 

 also in the pleural exudate. In the exudate they are usually 

 present in association with streptococci, and also with other 

 bacteria. They may also be found during the lung affection 

 in the nasal discharge. 



In repeating the investigations of Lignieres, Hntyra found the bipolar bacilli 

 only very exceptionally in the blood and in the nasal discharge of affected horses; 

 on "the other hand they were present in great numbers in the affected lungs, however, 

 usually associated with streptococci and also with other bacteria (colon bacillus, 

 bacillus pyocyaneus, and others). In the small hemorrhagic, or reddish brown, 

 hepatized areas the bipolar bacilli are usually present in great numbers, while they 

 lodge in the gray hepati2ed or gangrenous areas, aud in the pleural exudate, only 

 sparingly, or their presence cannot at all be demonstrated. The bipolar bacillus, as 

 well as tiie streptococcus, apparently exert their pathogenic action through toxins. 

 Filtrate of a bouillon culture of the bipolar bacillus, several days old, injected intra- 

 peritoneally into a horse in a dose of 500 g., produced symptoms of severe intoxica- 

 tion (rapid small pulse, diarrhea, profuse sweating). The filtrate of streptococcus 

 cultures is less toxic, nevertheless 350 cc. of the same injected intravenously may 

 also produce symptoms of severe poisoning which last for several hours. 



The presence of pyogenic streptococci in the nasal discharge, and in the 

 thoracic organs has also been established by other authors (Hell, Foth, JSven Wall, 

 Ostertag, Tartakowsky and others). Pfeiler observed after an intravenous injection 

 of bouillon cultures (35 to 120 cc.) persistent fever, nasal discharge, yellowish-red 

 discoloration of the conjunctivae, as well as serous or fibrinous inflammation of the 

 pleura, and in some cases also pneumonia. Tabusso found that cultures of the 

 bacillus equisepticus exert a severe toxic action, and that the intrapleural injection 

 may produce lobar pneumonia. Dreyer is of the opinion that the disease may be 

 transmitted with the fresh blood of affected horses. However, Ostertag proved in 

 his varied experiments, which he carried out for many years, that the typical disease 

 can be produced with neither of the two described bacteria, nor with the diplo- 

 bacillus, which he found in the nasal discharge and, more rarely, in the blood of 

 affected horses. He further showed that the disease cannot be transmitted to 

 healthy horses by means of the nasal discharge, exhaled air, pleural exudate, urine 

 and blood of affected animals. 



The experiments of Hempel & Pfeiler also speak against the streptococci and 

 bipolar bacilli as being the primary causes of the disease, as they failed to 

 demonstrate complement fixing substances for these respective bacteria in the blood 

 of horses affected with the disease. 



The view of Lorenz, according to which the cause of the disease is a pleomor- 

 phous micro-organism, usually present on the surface of the skin of the pastern, 

 is a priori extremely improbable and has never been substantiated by others. The 

 claim of Baruchello & Pricolo that the causative agent of the disease is a blood 

 spirochete, and the more recent assertion of Baruchello & Mori that it is a piro- 

 plasma, are contradicted by the fact that the numerous blood examinations of other 

 authors failed to demonstrate the presence of these organisms, and can be only 

 explained by assuming that these Italian authors studied a disease of horses which 

 differs from the influenza occurring in middle Europe. 



The etiological action of the bacteria found up to the present 

 in influenza cannot as yet he established accurately. For none of these 

 organisms has sufficient proof been advanced that they can produce 

 the disease primarily, and no one has ever succeeded in producing 

 croupous pneumonia in its typical course artificially. It is therefore 

 possible that the primary cause of the disease, or the infective agent 

 which transmits the disease from animal to animal, is a micro-organism 

 which is not yet known, and that the streptococci, as well as the ovoid 

 bacteria, which are normal habitants of the healthy air passages, exert 

 their pathogenic action only after the specific virus has already affected 



