132 MASTITIS OF THE COW 



removed from the cisterns and milk-ducts. Gangrene, 

 which is a common complication, produces a stinking odor 

 in the udder. 



The acute infections, as secondary infections, may in- 

 vade the chronic udder-infections, yet these are usually easy 

 to recognize by their particular post-mortem characteristics 

 (see later). 



A cut surface, hut slightly or not at all red-stained, 

 indicates ( 1 ) a chronic infection or ( 2 ) the healing process 

 of a bruise or of an acute infection. 



The chronic infections manifest their individual charac- 

 teristic post-mortem picture. From the autopsy point of 

 view they may be divided into typical stroma-infections and 

 typical milk-infections. 



The typical stroma-infections are pyobacillosis, tuber- 

 culosis and actinomycosis. They are usually easy to recog- 

 nize. If the condition is very early the diagnosis may be 

 difficult and the microscope must be used. 



Pyobacillosis. — The affected quarter is hard and mod- 

 erately swollen. The lymph-glands are not changed. 



Upon incising the lesion, the knife is smeared by a yel- 

 lowish-green, thick, caseous mass of salve-like consistency. 

 The cut surface is even and yellowish-gray. Its consis- 

 tency is firm. Here and there one observes variable-sized 

 cavities containing yellowish-green, caseous masses, which 

 are surrounded by thick connective-tissue walls, the in- 

 ternal side of which are smooth. The yellowish-gray lobuli 

 show no milk points, but not infrequently a few or more 

 small yellow, sharply defined necrotic or caseous points. 

 Pressure upon the lobuli causes yellow, caseous cylinders 

 to be expressed. Numerous milk canals are distended with 

 these yellowish-green caseous masses. Their walls have 

 become thick, white connective-tissue structures trans- 

 formed into fistula?. In other milk canals and in the cis- 

 terns one may observe spongy croupous membranes. The 



