80 MASTITIS OF THE COW 



Udder-pyobacillosis through wound-infection is distin- 

 guished by its localization in the neighborhood of the wound 

 and by a comparatively uniform distribution of the con- 

 dition from this point inward. Ulceration in the wound is 

 great and tends toward fistula formation. 



Secondary, or embolic udder- py oh acillosis is distin- 

 guished by a primary condition of the lungs and by its 

 position, which usually is in several quarters in the begin- 

 ning, seldom in one quarter alone. Should one quarter 

 alone be affected it is most likely to be a hind quarter. It 

 is further distinguished by large and somewhat uniform 

 distribution in the affected quarters in the beginning. ( The 

 condition is distributed in the lower parts in most instances, 

 however.) 



In the beginning these forms may be sharply separated. 

 Through development of the conditions they may become 

 somewhat similar. Thus, for example, primary udder-pyo- 

 bacillosis through wound-infection showing secondary 

 ulceration through the skin with subsequent fistula forma- 

 tion can become very difficult to distinguish from the other 

 forms. 



By ulceration through the milk-ducts pus containing 

 infectious organisms is emptied into the milk. This pus 

 can: (1) Be withdrawn with the milk without producing 

 any changes in the udder; (2) the infectious organisms can 

 be picked up in the milk by fresh leucocytes and be again 

 carried into the connective tissue, through which the in- 

 fection is spread further, and ( 3 ) the thick pus can remain 

 in the milk-ducts for a shorter or longer time, through which 

 the infection, as a secondary milk-infection, can cause more 

 or less necrosis of the underlying tissue and thus produce a 

 croupous inflammation. Upon desquamation of this 

 croupous membrane a wound is presented which likewise 

 becomes infected. 



Secondary infections are common and appear to aggra- 



