Infectious MammUis of Cows 967 



tained in pure cultures, and by which the typical affection can be 

 experimentally induced. 



Zschokke recognizes two types of the disease — the curable and 

 the incurable. The first is caused by a short streptococcus ; the 

 latter by a long streptococcus. Apparently this is a variation in 

 the \arulence of the same organism ; if very virulent it forms in 

 long chains if milder in short chains. 



Zschokke insists that the microscopical diagnosis is practical, 

 and fundamentally important. Not only would he differentiate 

 microscopically between acute mammitisand infectious mammitis, 

 but he would recognize, by the length of the cocci chains, the 

 grade of virulence in individual cases of infectious mammitis. 

 He considers the early bacterial diagnosis of the greatest import- 

 ance in order that control measures may be properly instituted 

 early in an outbreak. 



The handling of infectious mammitis or agalactia has proven 

 unisuccessful. No method of treatment has been found which 

 exerts any recognizable influence from an economic standpoint. 

 Zschokke tried intra-mammary injections of potassium iodide, 

 i-iooo, and itrol (silver citrate), 1-4000, but without result. He 

 also tried, in vain, subcutaneous and intra-mammary injections 

 of anti-.streptococcus serum. 



Cantharides and other stimulating applications to the udder 

 reduced the infection ; but the milk flow was suppressed, the 

 gland continued functionless, and the betterment was without 

 economic value. 



The experiments of Zschokke convinced him that it is best to 

 leave a milk gland, affected with infectious mammitis, wholly 

 alone. If the milk is drawn from the gland, the free leucocytes 

 are also extracted. If left alone, the leucocytes destroy the 

 streptococci, especially those in short chains. If the milk, or 

 mammary excretion representing it, is left in the gland, not only 

 do the leucocytes tend to destroy the cocci, but the spread of the 

 infection to other quarters of the udder or to other cows is obvi- 

 ated. So long as the infected excretions remain in the udder, 

 they do no harm to the gland, but the affected gland tends more 

 to recovery than if the excretions were removed. 



The most important feature of handUng the malady is the pre- 

 vention of its spread from diseased to healthy glands. Diseased 

 cows should be as well isolated as practicable, and should be 



