QUESTIONS AND ANSWEKS 277 



tain infectious diseases, such as foot-and-mouth disease, hog cholera, 

 etc. 



Discuss the etiology of infectious abortion in cows. Describe briefly 

 the course and symptoms of infectious abortion. 



(There are many conflicting opinions on all phases of this 

 disease.) 



Infectious abortion in cows is due to a short bacillus (bacillus 

 of Bang) which is carried from cow to cow by the bull, although 

 other means of transmission are recognized. Entering the uterus, 

 at the time of copulation, or later, it produces a catarrhal endo- 

 metritis with a fibrinous exudate which causes a separation of the 

 placenta from the uterine wall and abortion follows. Some authori- 

 ties think the infection enters by way of the digestive tract and 

 udder, and is carried by the blood to the cotyledons. In many cases 

 the infection remains in the system from a previous abortion. 



In the majority of eases abortion occurs at about the fourth to 

 sixth month of pregnancy. It may occur much earlier or very near 

 the end of gestation. The foetus is usually born dead, or, if alive, it 

 very rarely survives. A few days before abortion occurs, a yellow, 

 or reddish-tinged mucopurulent discharge is seen to escape from 

 the vulva. The latter becomes reddened and swollen. The milk 

 secretion lessens and finally, with very little straining or apparent 

 inconvenience, the foetus is expelled. In a great majority of cases, 

 portions of the after-birth are retained and a mucopurulent, blood- 

 tinged discharge follows for ten days or two weeks. The infection 

 remains in the internal genital organs for several months, so it is 

 quite common for the cow to abort a second time. After the second 

 abortion, the infection seems to disappear, or at least the animal 

 is immune to its effects. 



What methods should be employed in the control of an outbreak of 

 infectious abortion in a herd of cows? 

 Separate the infected from the non-infected. Burn aborted 

 foetuses, after-births, and soiled bedding. Disinfect stalls and gut- 

 ters. Irrigate the uterus of each aborting cow with a 1-1000 solu- 

 tion of potassium permanganate. Wash the external genitals of all 

 pregnant cows with the disinfectant. Separate attendants should 

 be assigned to the two divisions of the herd. The sheath of the bull 

 should be disinfected before and after copulation. A separate bull 

 might be used for infected and non-infected cows. Precautions 

 should be observed in introducing new animals into the herd. 

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