210 SWINE PRACTICE 



rounding's predispose to abortion in swine as well as in other animals. 

 Non-specific abortions are caused by high temperature, toxins of 

 various infective micro-organisms and perhaps by some other con- 

 ditions. The specific, causative micro-organism, if there is such, 

 of infectious abortion has not been identified, although a variety of 

 germs have been isolated from the aborted fetuses and uterine dis- 

 charges. It is possible that a combination of organisms or different 

 organisms will be found to be the general causative factors in the 

 production of this disease. From the information available, it is 

 advisable to consider this type of abortion in swine as infectious. 



DISSEMINATION 



Reports are available in which it has been demonstrated that an 

 aborting sow may be transferred from an infected herd into a herd 

 free from this disease and establish abortion in that herd. For ex- 

 ample, a sow from an aborting herd was purchased in one state by 

 a swine breeder in another state, the purchaser having had no previ- 

 ous trouble with abortion in swine, but within six months after the 

 inroduction of the newly acquired animal from the aborting herd, 

 over eighty per cent of the sows in the free herd aborted. Similar 

 reports seems to incriminate the boar as a disseminator of infection. 

 Whether or not the boar is merely a carrier of infection, or whether 

 he is affected with the disease, remains to be demonstrated. Some 

 breeders are of the opinion that contaminated feed is a source of 

 infection of this disease. Whether or not a premise is relatively 

 permanently infected after abortion occurs thereon has not yet been 

 determined. If the causative agent or agents of this disease are 

 resistant to exposure to atmospheric and climatic conditions, then 

 barnyard fowls, pigeons, dogs and vermin must be considered a 

 means of carrying infection. It may also be found that parasites, 

 such as lice and probably also vermin, may be found to be factors 

 in the spread of infective abortion in swine. 



SYMPTOMS 



Abortion usually occurs between the third and fourth month of 

 pregnancy and the breeder will have no difficulty in identifying 

 aborting sows. In some instances, the fetal membranes are not 

 sloughed and their retention favors infection which is usually suc- 

 ceeded by metritis and sometimes by the death of the sow. Sows 

 that have not sloughed the fetal membranes have a distressed appear- 



