TUBERCULOSIS OF THE COW 129 



than the matter discharged from the mouth or nostrils. We have 

 found that even in the case of cows with slight tuberculous lesions, 

 tubercle bacilli in small numbers are discharged in the faeces ; while 

 as regards cows clinically tuberculous, our experiments show that 

 the faeces contain large numbers of living and virulent tubercle 

 bacilli. 



The Commissioners also found that the inoculation of 

 large doses of tubercle bacilli, human or bovine, may result in 

 the excretion of tubercle bacilli in the milk of the cow and of 

 the goat without any disease of the udder being produced, and 

 that in the case of the human tubercle bacillus these bacilli 

 may, when large doses are employed, be present in their milk 

 for a long time after inoculation. 



The same important fact has also been demonstrated by 

 investigators abroad. For example, Eabinowitch and Kempner 

 examined the milk of 14 cows all reacting to tuberculin, but 

 only one of which exhibited clinical signs of udder disease. 

 Ten out of these 14 cows showed tubercle bacilli in the milk. 

 Also De Jong ^ examined 10 slightly affected tuberculous 

 cows, but clinically healthy, and found 3 which were excreting 

 tubercle bacilli through healthy udders. 



These results prove indisputably that tubercle bacilli may 

 and do gain access to milk from cows which clinically show no 

 signs of udder tuberculosis or indeed of any form of tuberculosis. 

 While this fact is of immense importance, it is yet possible to 

 exaggerate its significance. Infection with the tubercle bacillus 

 is largely a question of dosage, and while all tuberculin-reacting 

 cows must now be looked upon as possible sources, and all cows 

 with " open " tuberculosis as actual sources of tubercle bacilli 

 in milk, yet the available evidence shows that extensive 

 infection of the milk with the bacilli of tuberculosis is mainly 

 from cows either marked " wasters " or those suffering from 

 tubercular infection of the udder. 



On this account chief significance must still be attached 

 to the cows with udder tuberculosis, and information as to 

 the prevalence of this condition is most important. Dis- 

 tinguished veterinary authorities do not altogether agree on 

 this point, but the general consensus of opinion is that about 

 2 per cent of cows suffer from a tuberculous udder. 



1 Fortschritte der Medizin, 1908, vol. xxvi., Sept. 20. 



K 



