MILK-BORNE DISEASES 139 



three years old. Several breeders, dairymen, and 

 veterinarians to whom I have submitted this point 

 have unanimously concurred in the opinion that 

 early breeding does, in some degree, contribute to 

 the spread of tuberculosis among dairy cattle. 



VI 



It is not believed that there is any very great 

 danger of infection through drinking the milk of 

 cows afflicted with pulmonary tuberculosis. Pru- 

 dence and common sense alike suggest the avoidance 

 of milk coming from animals known to be afflicted 

 with tuberculosis in any form, but the element of 

 danger is not very great unless the udders and milk 

 ducts are affected.^' In many instances experiments 

 have been tried with a view of ascertaining whether 

 the milk of cows suffering from pulmonary tuber- 

 culosis is dangerous, when fed to other healthy ani- 

 mals. So far as I am aware, none of these experi- 

 ments have shown the danger to be very great, though 

 isolated cases of infection have been reported by 

 various observers, in which cows suffering from pul- 

 monary tuberculosis only, and free from any disease 

 of the udders, have given milk that has infected 

 other healthy animals. 



But the danger from the mUk of cows affected 

 with tuberculosis of the udder is very real and grave, 

 as the experiments of Martin and numerous other 



