ABORTION 301 



the knowledge that is already available, but against con- 

 tagious abortion the case is far less hopeful. 



The cause of bovine abortion is a small bacillus that does 

 not form spores and is relatively non-resistant to disin- 

 fectants. It is called B. abortus, or the Bang organism, 

 after the Danish veterinarian who first discovered it. The 

 organism has been found widely distributed in all parts d 1 

 the world, and there is no doubt concerning its causal rela- 

 tion to the bovine form of the disease. 



Nature of the disease. The disease is one that has a spe- 

 cific action on the pregnant animal, causing an inflamma- 

 tion of the uterus, with injury to the fetus or causing its 

 death. The general health of the animal is not affected to 

 any noticeable extent. The organism is eliminated at the 

 time of abortion, and for an indefinite period thereafter in 

 the discharges from the uterus. It has also been found 

 in the milk. 



The organism may be present for months before abortion 

 actually occurs, indicating that it is to be looked upon as a 

 chronic disease. Again, an animal may continue to elimi- 

 nate the abortion bacilli in the milk years after the last 

 abortion occurred or when no abortion has been known to 

 occur. The infection of an animal does not necessarily pro- 

 duce abortion, since this will depend on the extent of in- 

 jury to the fetus. The infected animals that do not abort 

 may be as dangerous to healthy animals as those that have 

 aborted. The fact that some unsuspected animals may thus 

 act as bacillus carriers makes it an especially difficult dis- 

 ease to control in a herd. 



The natural manner of infection is not known with cer- 

 tainty. It has been shown by experimental methods that 

 the infection may occur through the genital passages. It 

 is probable that, if infection occurs in this manner, it must 

 take place before or very shortly after conception, as, after 



