THE PELVIC CANAL 53 



compressed laterally, especially about the lower segment. The 

 line drawn from the posterior iliac angle to the symphysis 

 runs more perpendicularly. The pelvic passage also is nar- 

 rower from side to side. We know that the plane running 

 through the cotyloid cavities is least capable of expansion. 

 For this reason the passage of the foetus may be retarded. 

 The normally developed calf may be too large for such pelvic 

 dimensions, to prevent extraction. Such a calf is known as 

 relatively too large. These cases call usually for embryotomy. 

 As age advances pelvic dimensions change and the pelvic canal 

 widens. Therefore, an abnormal birth in a two-year-old, as 

 just described, does not mean an unfavorable prognosis for the 

 cow as a future breeder. 



The pelvis of the calf is very elastic and compressible. 

 As a consequence, a calf may be born alive although the 

 distance between the trochanters exceeds the transverse pelvic 

 diameter of the mother. 



THE IMPORTANCE. OF PELVIC DIMENSIONS IN OBSTETKICAL PRACTICE. 



In man, an exact estimation of the pelvic dimensions is 

 often of the greatest importance. The prognosis as to the 

 course of labor in a patient with an abnormal pelvis can only 

 be made after its diameters have been ascertained. It may 

 become necessary during pregnancy when fear exists that the 

 present pelvic deviations would not permit of a normal 

 delivery, and in order to save the mother's life artificial 

 abortion might be indicated (rachitic pelvis). 



In the cow, lessening of the pelvic diameters is not very 

 frequent. Malformations in man producing stenosis quite 

 frequently lead to an examination, but are exceedingly rare 

 in the cow. Animals with such abnormalities are not bred. 

 Nevertheless, it is desirable that the veterinarian be acquainted 

 with pelvimetry, for these reasons : 



1. The relationship between the diameters allows us to 

 form an idea of the shape and position of the pelvic bones and 

 contour of the pelvic canal. 



