50 BULLETIN 106, U. S. DEPARTMENT OF AGRICULTURE. 



that the organism is present in the milk of many herds; and that 

 vaginal discharges, feces, and milk must contaminate the food of 

 almost all cattle, the outlook for the control of abortion becomes 

 discouraging, if not hopeless. 



On the other hand, if we accept the original view of Bang that the 

 cervical canal is the usual avenue of invasion of the uterus, or adopt 

 our own view that it is essentially the sole avenue and that the inva- 

 sion must always occur prior to the sealing of the uterus, the outlook 

 becomes somewhat more favorable, though still a formidable task. 



The history of attempts to control contagious abortion is every- 

 where strewn with disappointment, and has opened a rich field for 

 much of the boldest quackery every practiced upon breeders. If our 

 views are correct, the presence of an aborting cow amongst pregnant 

 cows can have no danger because, if the utero-chorionic space in the 

 uteri of the pregnant animals is clean and the uterine seal is normal, 

 any infection eliminated by the aborting animal can not reach the 

 uterine cavity of a neighboring healthy cow. Common decency, 

 however, in the production of milk dictates that aborted fetuses 

 should be promptly removed in a sanitary manner and aborters 

 having retained placenta or vaginal discharges should be excluded 

 from the dairy till healed, and that soiled stalls or gutters should be 

 cleaned. 



Repressive laws against contagious abortion in cattle have been 

 proposed by various veterinarians, involving compulsory reporting 

 of outbreaks, quarantine of infected herds, exclusion of affected 

 animals from cattle shows, etc. So far as we know, no such laws have 

 ever been put in force. The wide dissemination of the disease, its 

 insidiousness, the uncertainty of its diagnosis, and other difficulties 

 make the application of such laws impracticable. 



The sale of aborting animals has been largely practiced by some 

 breeders and dairymen. It is a wasteful and hopeless process. Our 

 data indicate that 25 to 50 per cent of all cows ultimately abort once, 

 so that the dispersal process is an economic waste and it fails to check 

 abortion. 



It has generally been claimed that one abortion affords a large 

 degree of immunity. This is, according to our data, wholly erroneous. 

 The idea that one or two abortions should confer immunity against 

 future abortions is contrary to reason. It is the live mother and not 

 the dead fetus which needs to be immunized. There is no more 

 reason why a cow which has aborted shall thereby acquire an immu- 

 nity than that one which gives birth prematurely to a calf because 

 of the infection of contagious abortion in her uterus should become 

 immune, or that a cow suffering from retained placenta from abortion 

 infection, although the calf be carried full time and born healthy, 

 should be immune. 



