BUREAU OF ANIMAL INDUSTRY. 105 



PATHOLOGICAL DIVISION. 



John K. Mohi.ek, Chief. 



Dr. A. Eichhorn was Chief of the Pathological Division until his 

 resignation. Avhich took eti'ect December 81, 191G, after which Dr. 

 John 11. Mohler, assistant chief of tlie bureau, was placed in charge 

 of this division, in addition to his other duties. 



ABORTION DISEASE. 



Efforts to reduce the seemingly ever-increasing losses due to the 

 dissemination of infectious abortion of cattle have been continued. 

 The difficulty with which this disease is eradicated, even in herds 

 that are maintained under the most sanitary conditions, has served 

 to demonstrate that its avoidance is a relatively simple matter as 

 compared with its control when once the infection is established. An 

 endeavor has been made to take advantage of this feature in the 

 control measures undertaken by impressing upon stock breeders and 

 dairymen the importance of building up their herds by a breeding 

 rather than a purchasing process, and, in the event of its being neces- 

 sary to introduce new animals, of the care necessary for the avoidance 

 of dancer of infecting tlie original stock. Control measures based 

 upon sanitation have been advocated where the disease is already 

 present. 



Correspondence has furnished a means of supplying a certain 

 amount of information, but efforts have also been made to reach those 

 to whom the subject is vital by presenting exhibits and talks at many 

 of the meetings of the stoclanen's and dairymen's associations. The 

 preparation and distribution of a Farmers' Bulletin (No. 790) has 

 been the means of disseminating widely such facts in regard to 

 abortion as have been considered of most practical value to the 

 stock breeder and dairyman. 



The application of control measures under herd conditions has 

 received more attention than during previous years. The bureau 

 has under observation at the present time 20 herds of cows, compris- 

 ing approximately 3,000 animals, where different methods are being 

 used. In a number of these herds efforts have been made to reduce 

 the losses from abortion by applying sanitary measures alone. Bac- 

 terin treatments have been employed where a test of the animals has 

 indicated that the infection has existed in the herd for only a limited 

 period. In those herds wdiere a large percentage of the animals 

 have given positive reactions to the serum tests and abortions have 

 been frequent for a number of years an effort has been made to de- 

 velop an immunity or tolerance to the infection by the subcutaneous 

 injection of nonpregnant animals, two months at least before breed- 

 ing, with large doses of living abortion organisms, a method de- 

 scribed by the Board of Agriculture and Fisheries of England as 

 having been found effective. A sufficient Jength of time has not yet 

 elapsed to estimate the value of these various methods. An objec- 

 tion to the latter control measure has been the danger that animals 

 so treated may be actively infected and capable of disseminating the 

 disease if introduced into clean herds. A further study of this fea- 

 ture is contemplated. 



