50 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



losis were demonstrated on post-mortem examination. All new 

 cattle brought into the District have to be submitted to the tuber- 

 culin test, and it is also proposed to retest the herds at intervals so 

 as to detect any cases that may have developed since the first test. 

 As a result of this work the cattle of the District are already prac- 

 tically free from tuberculosis, and it is believed that by continuing 

 the retests for a reasonable time the disease will be completely 

 eradicated from the cattle of the District. 



Cooperation has also been extended to the States of Maryland and 

 Virginia in applying the tuberculin test to cattle in those States. 



HOG CHOLERA. 



The efficiency of the method of serum treatment devised by the 

 Bureau of Animal Industry for the prevention of hog cholera has 

 been still further confirmed by practical experiments during the past 

 year. A striking demonstration was made at the Kansas City stock 

 yards. Out of a lot of 35 pigs, 22 were injected with Bureau serum, 

 4 were inoculated with virulent hog cholera blood, so as to give them 

 the disease, and 9 were not treated in any manner. All were placed 

 in a pen together. The 4 inoculated pigs contracted hog cholera and 

 died, also the 9 untreated pigs, while the 22 pigs treated with serum 

 remained well. A similar experiment at South Omaha gave equally 

 good results. 



The Department has continued its efforts to encourage and assist 

 state officials in preparing the serum for sale or distribution to hog 

 raisers, and has also carried out scientific experiments with a view 

 to improving the methods and reducing the expense of producing 

 the serum. It has been shown beyond doubt that this serum is an 

 efficient agent for protecting hogs against hog cholera and that by 

 its use in a S3^stematic way this disease can probably be eradicated. 



SCIENTIFIC INVESTIGATIONS OF ANIMAL DISEASES. 



The Bureau of Animal Industry has continued its scientific inves- 

 tigations into the nature and cause of various diseases of animals. 

 Considerable attention has been given, as heretofore, to tuberculosis, 

 and especially to methods of immunizing cattle against this disease. 

 The only methods of immunization which have given promising 

 results have required the use of living tubercle bacilli, so that these 

 methods can not be considered free from danger, and the Department 

 is not yet prepared to recommend their use. 



Other diseases under investigation during the past year are lip- 

 and-leg ulceration of sheep, swamp fever of horses, chronic bacterial 

 dysentery of cattle, bighead of sheep, glanders of horses, rabies, and 

 anthrax. Experiments made at the suggestion of a European cor- 

 respondent with a new method for the diagnosis of glanders have 



