108 THE COW IN HEALTH AND DISEASE 



and, unless complications set in, the mortality is 

 very low. There is a type, however, known 

 as the malignant type, in which the mor- 

 tality is very high. This type is not very 

 common. It causes its greatest loss in the re- 

 duction of the productiveness of the animal, also 

 the loss of flesh. Fat animals that are almost 

 ready for market lose flesh very rapidly. With 

 milk cows the flow of milk is very rapidly dimin- 

 ished. It was said by a prominent veterinarian 

 in England, and one who had a prominent part 

 in handling the disease in that country, that the 

 loss to each cow giving milk was at least $20. 

 Taking into consideration the number of milk 

 cows in the United States, we wonder how 

 many times this loss, if every milk cow in the 

 United States would become affected, would be 

 the cost of the eradication of this last outbreak. 

 We should judge that it would be well into the 

 thousands at least. One attack of the disease 

 does not render the animal immune; it may 

 have several attacks of the same disease, and 

 besides, an animal that has apparently recov- 

 ered may carry the contagion to another 

 animal. These are known as virus carriers. 

 It is the loss of the milk flow and also 

 the loss of flesh that makes this condition 

 such a detriment to the dairy industry. It is milk 

 that they are after. Their aim is to develop cows 

 that will produce a large flow of milk that is 

 rich in butter-fat, and no cow that is poor and 

 weak and thin and poorly nourished can do this. 



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