Infections of the Ovum, Embryo and Fetus 517 



of infection. No matter what the identity of the infection 

 may be, the problem which he faces is disinfection, and he 

 elects that method which, in the present state of knowledge, 

 promises the best results. 



G. Symptoms and Diagnosis 



The symptoms and diagnosis of abortion are essentially 

 included in the definition given — ^the observed expulsion of 

 a fetal cadaver. The symptoms are those of parturition ab- 

 breviated. In early pregnancy there is no sinking of pelyic 

 ligaments, no enlargement of mammae, no marked dis- 

 charge from the vulva, no visible effort at expulsion. When 

 abortion occurs late in pregnancy, the pelvic ligaments may 

 sink as in parturition, the mammary gland may be en- 

 larged and the vulva may become tumefied, But any of 

 these phenomena may occur from other causes. 



After about the fifth month of pregnancy, in addition to 

 the observation of the expulsion of the fetal cadaver, there 

 may be retention of the fetal membranes, indicating that 

 abortion has occurred or that abortion is then in course. 



Abortion may be suspected or determined with confidence 

 upon other grounds. In the regular control of reproduc- 

 tion in cattle, pregnancy may be reliably diagnosed at 

 thirty to sixty days after coitus. If the diagnosis is clear 

 and definite, as it should ordinarily be, and it is later de- 

 termined that the pregnancy has ceased to exist and the ani- 

 mal has not calved, it is clear she has aborted at some time 

 between the two dates of observation. 



The diagnosis of pregnancy may be fairly secure upon 

 other grounds than clinical examination. If a cow or 

 heifer is regular in her estrual cycle, is bred, does not men- 

 struate after coitus, and estrum fails to recur at the regular 

 interval, it is good evidence that she is pregnant. If, after 

 a lapse of forty to ninety or one hundred days, estrum re- 

 curs, it is probable that an embryo has perished and has 

 been expelled. There are numerous other conditions which 

 may present the same history, but abortion is by far the 

 most probable explanation. 



