155 



chasing new subjects is, however, an unsatisfactory prac- 

 tice. All experience goes to prove this. For example, 

 Morck refers to a herd where the animals were sold off 

 as they aborted and new ones purchased to take the 

 place for a period of eight years without improvement. 

 The owner then resolved to keep the animals at all haz- 

 ards, and within two years abortion disappeared from 

 the herd. This method would be practicable where the 

 owner is prepared to sacrifice all exposed animals for 

 slaughter and begin business with new stock and in dif- 

 ferent (|uarters. A cow, it matters not how valuable her 

 milking qualities, should never be sold for breeding pur- 

 poses if she is suspected of having infectious abortion. 



4. There is another recourse for the breeder; he can 

 establish immunity in his herd. This will, perhaps, en- 

 tail the loss of two or three calves, for each cow, and a re- 

 duction of milk during as many periods of lactation, 

 but, after all, it is doubtles the most economical course 

 to pursue. 



In making uj) a forecast for a line of treatment we 

 are reminded that cows which miss one calving period 

 and abort before the next or those which carry almost 

 full time, often give a full flow of milk, seeming to 

 suffer no inconvenience from the mishap. Also the num- 

 ber of living calves delivered by aborting cows implies 

 that it may be possible to bring the infected cow to 

 the full period of pregnancy, thereby securing a viable 

 calf. Then, presupposing irritation, as previously inti- 

 mated, to be the active cause of abortion, the first ob- 

 ject of treatment should be to tide animals which show 

 signs of aborting over the crisis by giving anodynes. 

 Such a course of treatment gave highly satisfactory re- 

 sults at the Vermont Experiment Station. After four 

 abortions had occurred three out of nine other cows 

 pregnant, showed signs of aborting, but 'the act was pre- 



