lo Sept.. 1910.] Abortion in Coivs. 561 



One point of great importance is tiie fact tliat cows wliich abort when 

 they are well advanced in calf are apt to retain portions of the cleansings, 

 and these portions are expelled at irregular intervals as they break down 

 within the womb. This is accompanied by a more or less continuous slimy 

 discharge. Such a cow naturally becomes for a long period a source 

 of infection for others, and not only that, but she is almost certain to 

 contaminate the bull, who although himself not suffering from any diseased 

 condition, .thus becomes the carrier of the germs to other cows. The result 

 is that other cows served by such bull, very often either fail to conceive, or 

 having conceived, abort at such an early date, that this is only shown by 

 their manifesting again a desire for the bull, when that is unexpected. 

 In other words, the disease is very apt by this means, to develop into 

 what may be termed a contagious form of sterility, or barrenness. 



The lecturer detailed what he had found to be a common history of 

 the introduction and the result of the disease in various herds : — 



A dairy factory becomes established in a district where formally 

 dairying was not actually much in vogue. Various farmers agree to 

 supply the factory with milk, and it becomes necessary for them to increase 

 their herds in order to do so. The sale yard is visited and cows purchased 

 from various sources. Shortly after the introduction of these cows to the 

 herd one aborts ; other cases, at various intervals, may follow. As the 

 cows are perhaps near the time of calving, the exact date of which is 

 not known, and they give a certain supply of milk, probably little atten- 

 tion is paid to the circumstance, especially as the calves may be of little 

 value to the owner. The aborted cow or cows, in due course, are put to the 

 bull ; they do not conceive, but come in heat again later on. Meanwhile, 

 other cows have calved in the natural way. These are served by the same 

 bull, and also become barren, or abort within a few -weeks of conception. 

 The result is that the owner sees a bad outlook for next year, for although 

 some of them may ultimately get in calf, many do so at such a late period 

 that it means a loss of the milk supply for next year, through the cows 

 calving late in the season. Too often the owner considers the fault to lie 

 solely with the bull. Imagining he is impotent, the owner turns him into 

 the sale yard, where he is bought by some other unsuspecting dairyman, 

 and so spreads the seed of trouble in a new herd. This phase of the 

 contagious form of barrenness, or sterility, becomes thus, m many dairying 

 districts, a more serious condition than the phase of actual abortion, for 

 the season's milk supply of a cow is often worth as much, if not more, 

 than the cow herself. The lecturer had known of cases where farmers 

 had found it impossible to get more than 20 or 30 per cent, of their cows 

 in calf, entirely as a result of this condition. 



Natural and Acquired Immunity. 



Returning to true abortion, or the actual expulsion of the immature 

 foetus, it was pointed out that apparently no pregnant cow was naturally 

 immune, or free from the possibilities of aborting as the result of infection. 

 It had been observed, however, that after one and especially two attacks 

 had been completely recovered from, the animal was very unlikely to abort 

 for a third time, this being evidently due to a definite degree of immunity 

 having been acquired. 



Experimenters had thought that it might be possible to artificially 

 confer such immunity, and experiments were now under weigh to test a 

 definite plan of so doing. It has been found that an empty non-pregnant 

 cow may withstand with impunity enormous doses of artificial cultures of 

 the abortion bacteria, introduced by the mouth, or under the skin. He 



