Tuberculosis. Ill 



In the European countries, where dairying has long 

 l>een carried on, the disease is very widespread. In soma 

 of the German states 30 per cent of the cattle are dis- 

 eased ; in Belgium 48 per cent ; in Denmark after fifteen 

 years of warfare against it, the percentage of dairy 

 cows affected has been reduced from 40 to 10 per cent; 

 in England 35 per cent of the cattle are affected. In 

 some of our eastern states, as Massachusetts, 26 per cent 

 of the dairy cows have the disease. The amount of the 

 disease is less in the western states, probably from 5 to 

 10 per cent of the milch cows of Wisconsin, Minnesota, 

 Iowa anji Illinois are affected. 



It is not evenly distributed, but is most prevalent in 

 those districts where improved dairying has been longest 

 carried on, and where buying and selling of milch cows 

 is general, as in the districts furnishing milk to the cities. 

 It is more often found in pure-bred herds than in those 

 of common stock, not because pure-bred cattle are more 

 susceptible, but because more animals are bought into 

 and sold from such herds. There is little or no differ- 

 ence in the susceptibility of the various breeds; Jerseys 

 are free from it on the island of Jersey, but acquire it, 

 when brought in contact with diseased cattle. The beef- 

 breeds are as easily infected as any of the dairy breeds. 

 It is more often present in large herds than in small 

 ones, as each animal purchased may be the means of in- 

 troducing the disease into the herd. 



Distribution and appearance of diseased tissues. 

 The disease is commonly associated with an affection of 

 the lungs and indeed this organ is most often attacked. 

 Every part of the body, however, may be diseased heart, 

 liver, spleen, muscles, brain, and skin may be affected. 

 The lymph glands that are found in the neck, along 



