Sigrts of Pregnancy 385 



The diagnosis of pregnancy during its earlier stages is exceed- 

 ingly difficult and, during the very earliest period, is impossible. 

 The symptoms of pregnancy may be divided into three principal 

 groups : the subjective or physiologic signs ; the objective signs ; 

 and the positive or direct signs, which are observed by ex- 

 amination of the parts in a way to definitely determine the pres- 

 ence of the fetus itself. 



Physiologic or Subjective Signs. 



Some of the physiologic, and psychic, manifestations of pregnancy 

 are quite well marked, but tend in some cases to become decep- 

 tive. The physiologic symptom upon which the greatest re- 

 liance is placed is the cessation of estrum. As a general rule, 

 fertilization stops the appearances of estrum very promptly and 

 permanently throughout gestation. Estrum may not cease im- 

 mediately upon fertilization, but continue to the close of the 

 normal estrual period during which the impregnation has taken 

 place. Perhaps in this case we should rather say that the 

 estrum continues until ovulation and fertilization have occurred. 

 In discussing the relationship between estrum and ovulation, 

 we ventured to suggest that in some animals, if not in all, 

 but especially in the cow, ovulation does not occur until 

 near the close of the estrual period. Consequently fertil- 

 ization does not take place until such time, and until then 

 we cannot expect a cessation of ' estrum. In other words, 

 copulation, even though it be eventually fruitful, does 

 not mark the period of fertilization. However, it is generally 

 noted that, if copulation occurs early during estrum and 

 fertilization follows, the estrual period seems to be cut short. 



Not only do the symptoms of estrum usually disappear to not 

 recur until after parturition has taken place, causing the female 

 to persistently refuse copulation, but it is said by some observers 

 that males themselves in many cases decline to copulate with 

 females which are pregnant. This is not uniformly true by any 

 means. Both in the mare and cow there are frequent cases in 

 which the pregnant animal shows all the signs of estrum and in 

 which prompt and repeated copulation occurs in an apparently 

 natural way. This is especially true in nymphomaniac cows, 

 which frequently show all the signs of estrum, at the regular in- 

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