TUBERCULOSIS 73 



bacilli in milk quite frequently occurs not only from 

 cows that have advanced tuberculosis, but often even 

 from animals which react to the tuberculin test, but 

 show no clinical signs of disease. Numerous investiga- 

 tions (Bang,Nocard,Ostertag and several others) do not 

 agree with the results of Rabinowitsch and Kempner. 

 It appears to be probable that an excretion of tubercle 

 bacilli in the milk takes place only when lesions of tuber- 

 culosis are present in the udder tissue ; but these may be 

 so young and small that they are not apparent upon 

 clinical examination, and are also difficult to see in dis- 

 section. It is not impossible, however, that when bacilli 

 circulate in the blood in great quantity they may pass 

 directly into the milk; but this cannot be a frequent 

 occurrence. As early stages of udder tuberculosis are 

 not revealed by clinical examination, one must act upon 

 the assumption that not only cows with evident udder 

 or miliary tuberculosis give milk containing tubercle 

 bacilli, but also that this may be the case with many cows 

 having advanced tuberculosis, yet without changes in 

 the udder that can be detected by clinical examination. 

 Even cows that are apparently affected with tubercu- 

 losis only to a slight degree, or those that appear by 

 clinical examination to be perfectly sound, may give 

 tuberculous milk, in some cases, because very early 

 metastases occur to the udder and in others because this 

 organ appears occasionally to be the seat of primary 

 tuberculous infection. 



It has been claimed that cows even those appearing 

 clinically sound frequently give milk containing tuber- 

 cle bacilli after a tuberculin reaction and, therefore, it 

 has been advised to prohibit the use of unboiled milk 

 from such cows, for a few months after the tuberculin 

 test. This assertion is wholly untenable and is com- 

 pletely lacking in proof. 



