The Diagnosis of Pregnancy 1 13 



the ovum escapes into the peritoneal cavity, and conception 

 is barred for that estrual period. 

 Recent estrum is recognized : 



( 1) • By menstrual blood in the vagina or the soiling of the 

 tail and buttocks with blood, about twenty-four hours after 

 estrum has ceased ; 



(2) By engorgement of the uterus which continues during 

 menstruation ; 



(3) By the rapid atrophy of the corpus luteum of the pre- 

 ceding estrum ; 



(4) By the palpation of the crater of the ruptured ovisac. 

 The diagnosis of estrum may be rendered more certain by 



concentrating the observations to a brief period. Thus, 

 when the soiling of the tail and buttocks with menstrual 

 blood is observed, if the breeder will watch the animal closely 

 from the eighteenth to the twentieth day thereafter and. 

 take occasion to place the cow in paddock or field with the 

 bull or other cattle, estrum will in all probability be recog- 

 nized. The time during which close watch is to be kept may 

 be even further concentrated by dislodging the corpus lu- 

 teum when it is well formed and watching the patient from 

 the third to the fifth day thereafter. 



D. The Diagnosis of Pregnancy 



The accurate diagnosis of pregnancy in the cow is a fun- 

 damental necessity in the handling of diseases of the genital 

 organs. The gravest and most embarrassing errors made 

 in dealing with the genital organs are the failure to diag- 

 nose an existing pregnancy and the erroneous diagnosis of 

 pregnancy when the animal is sterile. The failure to recog- 

 nize an existing pregnancy frequently leads to instrumental 

 abortion or to the slaughter of a valuable pregnant animal 

 which is wrongly believed to be sterile. The diagnosis of 

 pregnancy, when the animal is sterile, leads often to months 

 of expensive delay in breeding. The examination for preg- 

 nancy of valuable animals which are for sale is gradually 

 assuming scientific and economic importance. In some 

 large herds placed in dispersal sales, all the cattle are ex- 



