22 MASTITIS OF THE COW 



ever mechanically hinders this repulsion, and the necrosis 

 also prevents a strong attraction for the leucocytes. In 

 defence of the body the leucocytes are finally attracted to 

 the necrosis, and now the infectious organisms are sub- 

 jected to the action of these cells which inhibit their growth 

 and toxin production. The weakened infectious organisms 

 can then be rendered innocuous or killed or be dislodged 

 with the necrotic masses and be discharged with the milk. 



Through desquamation of a necrotic, croupous or diph- 

 theritic membrane a milk-infection can develop into a sec- 

 ondary stroma-infection. Following such desquamation a 

 wound is formed which can become infected (wound- 

 infection. ) In this manner a sequestrating purulent inflam- 

 mation with nodular necrosis is produced, constituting a 

 secondary stroma-infection or interstitial mastitis. Fol- 

 lowing complete softening of the sequesters the area is 

 changed into an abscess with a thick fibrous wall, which is 

 produced by inflammatory proliferation of the adjacent 

 connective tissue. 



In diiFuse necrosis mastitis as a sequestrating inflam- 

 mation naturally cannot proceed further than the periph- 

 ery of the diseased quarter of the udder. 



Milk. — The milk, which is changed by the primary 

 lesion, is further altered by the inflammation. It is ex- 

 tremely rich in cells and therefore purulent, thick and 

 pulpy. Its color is yellowish-gray, due to the presence of 

 cells, and it often contains croupous membranes as thick 

 yellow shreds. The reaction is somewhat strongly alkaline. 

 The milk never contains clumps of casein. [Kitt and 

 Jensen describe casein clumps in morbid milk.] 



Complication with Saprophytic Invasion. — Under 

 the usual conditions pathogenic bacteria, but not sapro- 

 phytes, may invade the milk in the udder. If the latter 

 do gain entrance they are taken up by the leucocytes and 

 destroyed. It may be difl'erent in other conditions such as 



