Diagnosis of the Duration of Pregnancy 129 



8. Diagnosis of the Duration of Pregnancy 



It is highly important that the veterinarian shall be able 

 to diagnose with reasonable accuracy the duration of an ex- 

 isting pregnancy. As already related, the heifer or cow 

 sometimes comes in estrum and is re-bred perhaps repeat- 

 edly after conception. It is then desirable to be able to 

 state, approximately, the stage of pregnancy in order that 

 it may be determined at about what period parturition may 

 be anticipated. When heifers or cows are bred in pasture 

 so that the date of conception is practically unknown, the 

 determination of the duration of pregnancy is at times 

 sought by the owner. In pedigreed cattle, when pregnant 

 females come in estrum, the bull is sometimes changed and 

 confusion of pedigree results, which may often be satisfac- 

 torily solved by physical examination to determine the dura- 

 tion. Sometimes conception occurs unexpectedly and a de- 

 termination of the stage of pregnancy aids in determining 

 how it occurred. Thus in one instance, in a cow supposed 

 to be non-pregnant which showed no estrum, examination 

 led me to say that she was pregnant four months. The 

 owner was certain she had not been served, but it was 

 finally recalled that four months previously a bull, supposed 

 to be too young to copulate, had been with her at pasture. 

 In another instance a pure-bred Holstein cow purchased a 

 year previously as pregnant six months, had not calved, had 

 not been in estrum so far as known, and, according to his- 

 tory, had at no time been where a bull could copulate with 

 her unknown to the custodian. In addition, her vagina con- 

 tained a quart or more of highly fetid pus. In spite of such 

 a history, I pronounced her pregnant six months and the 

 fetus alive. She calved true to diagnosis. When the custo- 

 dian saw clearly that the cow was to calve soon, he recalled 

 that she had, at the date indicated, escaped to the premises 

 of a Shorthorn breeder, though it was not known that she 

 had copulated with the Shorthorn bull. 



During the first five or six months, the stage of preg- 

 nancy in cattle is to be determined by the transverse diame- 

 ter of the pregnant horn of the uterus. During the latter 

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