PREVENTIVE MEDICINE 237 



were 83 per cent, reactors, and these had decreased to 4 8 per cent, 

 in 1912. 



As far as this country is concerned, MTadyean, in his report 

 to the Tenth International Veterinary Congress, has very ably 

 analysed the subject of the eradication of bovine tuberculosis and 

 one cannot do better than quote in exienso from his report : 



" At least, as regards Great Britain, the two main reasons why 

 the method of Bang has not been practised on a large scale are : 

 (1) absence of incentive in the shape of expected return for the 

 expense and trouble involved in eradicating the disease; and (2) 

 lack of facilities for maintaining complete separation between the 

 diseased and the healthy animals. ... (1) because there is little or 

 no demand for milk derived exclusively from non-tubercular cows ; 

 and (2) because the public have no trustworthy means of assuring 

 themselves that the milk which purports to be from tubercle- free 

 cows is really so. . . ." 



" A survey of what has been accomplished up to the present 

 time compels one to admit that no substantial progress towards the 

 complete eradication of tuberculosis has been made. This failure 

 is due to the inherent difficulties of the problem and to the fact that 

 to most owners the prospects of ultimate gain do not appear to 

 counterbalance the certain trouble and expense involved in an under- 

 taking which is not even sure of success. In this connection it 

 must be recognised that the conditions and circumstances are not 

 identical in all countries. Factors of very great importance in 

 determining the ease or difficulty of eradicating tuberculosis from 

 any country are the average size of the herds, the individual value 

 of the animals, the frequency of interchange of animals from one 

 herd to another, and the proportion of herds still remaining free 

 from the disease. To deal with the last point only, it would appear 

 from the statistics published by Regner that at the beginning of 

 the campaign against the disease in Sweden, out of a total of 1336 

 herds tested 534 (or 31 per cent.) were found to have no reactors 

 in them. It is certain that in Great Britain the proportion of 

 tubercle-free herds is far less than this, and among the principal 

 milking breeds (Shorthorns, Ayrshire, and Jersey) it is doubtful 

 whether it is as high as 5 per cent. 



" The experience already gained, especially in Denmark and 

 Sweden, indicates the great difficulty of freeing a herd from tuber- 

 culosis when the older animals are not tested at the outset, and 

 also when, after such a preliminary test, the non-reacting old 

 animals are regarded as certainly healthy and used as the nucleus 

 for forming a healthy herd. In the former case there is the 



