174 Influenza of Horses. 



in which, the exudate contains streptococci in great njimlje^'^n 

 in addition to the bipolar bacilli. 



The bipolar bacilli may sometimes be deraonstrfi.ijed. in th^,, 

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

 quently found in the hepatized 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 affectioc.. 

 in the nasal discharge. 



In repeating the investigations of LigniSres, Hutyra found the bipolar bacilli 

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

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

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

 bacillus pyoeyaneus, and others). In the sntiall hemorrhagic, or ^reddish browk, 

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

 lodge in the gray hepatized or gangrenous areas, and in the pleural exudate, only 

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

 weir as the streptococciis, 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 (rapfd small pulse, diarrhea, profuse sweating). The filtrate of streptococcus 

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

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



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

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

 Ostertag, Tartakqwsky and others). Pfejler observed after an intravenous injection 

 of bouillon cultures' (35 to 120 ce.) persistent; feyer, 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 eqxiisepticus 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 iriany 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 ra,rely, 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 pasterii,' 

 is a priori extremely improbable and has never been substantiate^ by Others.,- 'The 

 claim of Baruchello & Prieolp that the causative agenV, of the, disease is a blood 

 spirochete, and the more recent assertioi of Baruchello ffi 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' flisease St horses which 

 differs from the influenza Occurring in middle T3urope. « " 



The etiological action of the bacteria found up to the present,, 

 in influenza cannot as yet be established accurately. For none "of, these 

 organisms has sufficient proof been advanced thg,t 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 f foin 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 af tpr the specific virus has already affected 



