28 MASTITIS OF THE COW 



the exterior in external wounds, or in internal wounds be 

 forced or desquamated toward the interior into the milk. 



In nodular necrosis following milk-infection or in em- 

 bolic necrosis following infection through the blood, the 

 necrotic material cannot be gotten rid of as such, but it can 

 be liquefied through the action of the infectious organisms 

 and the cells of the inflammation (so-called suppurative 

 softening). The pus formed in this manner can empty 

 itself through the milk passages (in which the primary 

 embolic stroma-infection thus induces a secondary milk- 

 infection ) or directly to the exterior through ulceration of 

 the skin. The latter, ulceration of the skin, occurs how- 

 ever only in superficial nodules. In other cases complete 

 or only partially liquefied areas of necrosis can become 

 encapsulated following a stronger proliferation of periph- 

 eral connective tissue. This condition is then chronic. 



The Milk. — In externally infected wounds which have 

 not progressed to a milk-infection, the milk is only slightly 

 or not at all altered. The quantity, however, is more or 

 less diminished. 



In internally infected wounds the milk possesses the 

 same character as in the milk-infection [parenchymatous 

 mastitis]. 



A complication with saprophytic invasion can occur and 

 develop into an exudative gangrene. The exudate is stink- 

 ing and less densely fluid. 



Blood-infection. — Bactercemia. — In addition to en- 

 tering the milk, infectious organisms of a high virulence can 

 enter the blood stream through the opened blood-vessels 

 of a fresh wound or through the walls of the vessels injured 

 in the primary lesion. In this manner an acute blood- 

 infection can take place, which, if not fatal, leads to sub- 

 sequent disease processes as infectious pneumonia or 

 arthritis. 



Intoxication. — Stroma-infection can also result in 



