744 Infectious Abortion. 



Pathogenesis. The contagion wliicli readies the vagina 

 through copulation passes into the uterus, where it multiplies 

 on the surface of the mucous membrane, and later also on the 

 fetal membranes. The bacteria that reach the vagina during 

 pregnancy are evidently capable of passing the mucous plug 

 of the neck of the uterus, whereupon they multiply between the 

 fetal and mucous membranes. The bacilli may also reach the 

 mucous membrane of the uterus from the intestinal canal by 

 means of the blood stream, either before or after conception; 

 since it appears that this organ is an exceedingly favorable 

 medium for their propagation. 



The infective material produces an inflammation, as a re- 

 sult of which a fibro-purulent exudate forms between tlie 

 mucous membrane and the chorion, which loosens the contact 

 of the layers of tissues, and finally causes a partial detachment 

 of the fetal membranes. The inflammatory process extends in 

 the meanwhile also to the layers of connective tissue between 

 the chorion and allantois, as well as to the navel cord, on ac- 

 count of which they acquire a gelatinous appearance, on the 

 other hand the bacteria may also pass into the body of the 

 fetus either through the circulation, or by means of the amniotic 

 fluid. 



In consequence of the loosening and detachment of the 

 fetal membranes abortion may occur in various stages of 

 gestation; at times, however, the uterine catarrh does not 

 cause expulsion, but only the death of the fetus, in which case 

 there is formed a gradually accumulating exudate around the 

 fetal membranes, enclosing a shrunken mummified fetus. Later 

 this exudate becomes inspissated, assuming a tenacious gela- 

 tinous consistency and in this the abortion bacillus may remain 

 viable even for nine months after the death of the fetus (Bang). 

 The fact that the bacilli remain alive for so long a time in 

 the uterus explains the etiological connection in the abortions 

 that occur in an advanced stage of pregnancy as a result of 

 infections occurring during or even several weeks before copula- 

 tion. It also explains the cases of abortion in females that 

 have previously aborted but were not exposed to any new 

 infection in the meantime. 



Eepeated abortion reduces the otherwise very great sus- 

 ceptibility to new infections. Cows abort quite frequently a 

 second time, but a third abortion is exceptional. The reduced 

 susceptibility of the animal, and possibly the decreased viru- 

 lence of the virus is also evidenced by practical experience 

 upon certain farms where abortion occurs in progressively later 

 stages of gestation, and finally by the fact that the respective 

 animals, if they conceive at all, carry their pregnancy to term 

 in spite of the infected surroundings (Sand). 



Symptoms. Cows are most likely to abort in the fifth or 

 sixth month of pregnancy, mares in the fourth to eighth month, 



