344 VETERINARY BACTERIOLOGY 



by vaginal injections into the cow, guinea-pig, or rabbit. Nowak 

 succeeded in producing typical abortion of dead feti in guinea- 

 pigs and rabbits by intraperitoneal and intravenous injections. 

 He did not succeed by intra vaginal injections. 



Character of Disease and Lesions. There are few symptoms 

 either preceding or following the expulsion of the fetus. The 

 infection seems to result in the death of the fetus, and the organism 

 can be readily isolated in pure culture from such. Bang regards the 

 disease as a specific uterine catarrh. 



Immunity. It is known that cows that have aborted one or 

 more times may become immunized against the disease. Vaccina- 



.4 --,* - ; 



' 'H 



^P Mi -jf 



' 



Fig. 143. Bacillus abortus, colonies on serum agar (Nowak). 



tion and serum treatments have been attempted, but their worth 

 has not been thoroughly proved. 



Bacteriologic Diagnosis. Bacteriologic diagnosis may be made 

 certain by the isolation of the specific organism in culture as 

 outlined above. A tentative diagnosis may be made by pre- 

 paring stained mounts, and demonstrating the presence of a short, 

 gram-negative bacillus in the uterine exudate and in the blood 

 and tissues of the fetus. 



Transmission. The disease is probably most frequently trans- 

 mitted by the bull. Infection may also occur from other cows, 

 from infected stables, and bedding. 



