270 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



thrifty and weak, either as a result of poor feed or hardship during 

 shipment, they may not be able to stand dippiufr in a solution which 

 would be entirely without effect on perfectly strong and healthy ani- 

 mals. If the dip is imperfectly mixed, if it is prepared in such a way 

 that it tends to separate or '" break," if it is too warm, or if the sheep 

 are kept in too long, injury may result. Generally, however, these 

 factors will not cause serious loss in healthy sheep unless there is a 

 marked " break " or separation of the dip, in which case there is a sepa- 

 ration and concentration of the irritating part of the dip. If the sheep 

 have been driven long distances, or subjected to physical hardships, 

 loss is more apt to follow than in those which have not been subjected 

 to such treatment. The above facts lead inevitably to the conclusion 

 that in dipping sheep it is essential to perform all operations with 

 extreme care and accuracy. 



HOG CHOLERA. 



The work in connection with hog cholera has been along the same 

 lines as those pursued during the preceding year, the efforts of the 

 Bureau being directed chiefly toward assisting state officials in begin- 

 ninj? the work of producinir serum for immunizinir hoes against 

 hog cholera according to the method successfully developed by the 

 Bureau. This has been done through advice by letter and by ex- 

 plaining to state representatives personally at the Bureau's, experi- 

 ment farm at Ames, Iowa, the methods of producing tlie serum and 

 in furnishing a limited amount of serum and a few immune hogs to 

 States that were just starting the work. In addition, a limited num- 

 ber of practical demonstrations have been carried out successfully in 

 Mar3'land, Virginia, Illinois, Missouri, lovra, Kansas, Kentucky, and 

 Tennessee. ]Most of these demonstration experiments consisted in 

 treating a part of a diseased herd and leaving the remainder un- 

 treated. At Kansas City, Mo., however, a more thorough test was 

 carried out, tlie results of which were so interesting and demonstrated 

 so conclusively the efficiency of the serum as a preventive for hog 

 cholera that an outline of it seems desirable. 



The test was made in the stock yards at Kansas City, upon the 

 request of the Kansas City Live-Stock Exchange and of individuals 

 interested in this subject. Thirty-five 5'oung shoats were purchased 

 from a farm where hog cholera had not existed. These pigs, having 

 been carried to the Kansas City stock yards, and being in charge of a 

 committee appointed by the exchange, were treated as follows: 

 Twenty-two were injected with anti-hog-cholera serum prepared by 

 the Bureau. Four were injected with vindent hog-cholera blood. 

 Kine were not treated in any manner. All were placed in a pen 

 together. As was expected, the 4 pigs inoculated with the viiiilent 

 blood contracted hog cholera within a short time and all died. The 

 9 "checks" contracted hog cholera from those which were inocu- 

 lated with hog-cholera blood, and they also died. The 22 pigs 

 treated with the serum remained well, with the exception of one or 

 two, which were slightly affected on one or tAvo days. It is not 

 certain, however, that the trouble with the immune hogs was hog 

 cholera, as none died. All of the autopsies on the check animals 



