758 Veterinary Obstetrics 



Normally the fetus, until just prior to birth, lies somewhat up- 

 on its side with all the limbs flexed along the ventral surface of 

 its body, the radius upon the humerus and the metacarpus upon 

 the radius in such a way that the very long limbs of the foal 

 and calf occupy the least possible space in the uterus. When ex- 

 pulsive efforts set in, should the fetus be dead, the limbs may 

 remain flexed during parturition, just as they were prior to the 

 beginning of that act. Should the fetus be alive, it is quite pos- 

 sible that, because of close investment by the fetal membranes, 

 its feet may not become extended upon the carpus. Consequent- 

 ly the fetus approaches the pelvic inlet with the limbs still flexed, 

 in which case they almost inevitably become impacted in the 

 pelvic cavity, or beneath or against the pubic brim, to constitute 

 a more or less serious obstacle to delivery. 



Some obstetrists hold that the displacement may occur other- 

 wise. They claim that at the moment when the limbs of the 

 fetus enter the pelvic inlet they may not be fully extended, and 

 the toes may become caught against the border of the pubis. 

 As the fetus advances the limbs become flexed at the carpus, and 

 later the metacarpus and phalanges become directed backward, 

 and the folded limbs thus applied against the neck. If we study 

 carefull}'^ the mechanism here proposed, we find it probable that, 

 if it came about in this manner, when the parts became folded 

 the carpus would be far advanced in the pelvis along the side of 

 the neck of the fetus. This, as every obstetrist well knows, is very 

 rarely the case, but instead the flexed carpus is engaged against 

 or beneath the pubic brim, a position which it could acquire only 

 with the greatest possible difficulty, by the method which has 

 been suggested. 



Another objection to the tlieor)^ of the flexion of the carpus 

 during parturition may be realized by the obstetrist when he at- 

 tempts to extend the flexed member so as to bring about the 

 extraction of the fetus. He finds at once that the length of the 

 metacarpus exceeds the perpendicular diameter of the pelvis and 

 that the limb has to be pushed completel}' back into the abdomen 

 in order to be extended. If the mechanism of this flexion, as found 

 in dystokia, is of the character here alleged, when the flexion is 

 coming about it would tend to become stopped by the carpus 

 abutting against the sacrum and becoming lodged in a perpen- 

 dicular position across the pelvic inlet. 



