366 Veterinary Obstetrics 



tween ii and 16 inches or J^^ to |- the length of the fetus, a 

 difference which regularly leads to its rupture during the ex- 

 pulsion of the fetus and only rarely permits the birth of the calf 

 with the cord intact. Hence, in the cow and other ruminants, 

 not only is the fetus born naked, as already related, but during its 

 expulsion the rupture of the cord usually frees it completely from 

 all fetal annexes. 



In the pig, the umbilic cord is wholly amniotic and very long, 

 equal to the entire length of the fetus, while, in carnivora, the 

 cord is short and very resistant, so that eventually it is usually 

 bitten in two by the mother. 



In relation to diseases of the new-born, it should be noted in 

 reference to the various structures of the umbilical cord that, 

 when it is permitted to rupture naturally, the umbilical arteries 

 quickly retract within the abdominal cavity and draw along with 

 them, in an inverted manner, the loose connective tissue surround- 

 ing them. It has been claimed by some, apparently on insuffi- 

 cient grounds, that, in the cow, etc., the arteries rupture within 

 the abdomen. This retraction of the arteries accomplishes two 

 important purposes : it draws their wounded ends away from the 

 exterior, preventing the entrance of infection into them, and the 

 inverted connective tissue which is drawn back with them, offers 

 an impassable barrier to hemorrhage. The retraction of these 

 arteries also causes a thickening of their walls, as their length 

 decreases, and thus serves to narrow and virtually obliterate their 

 cavity. (See Fig. 56.) 



The umbilical vein remains open for a time and serves as an 

 avenue for infection. This fact is highly important in relation 

 to the well-being of the young, since, through this portal, serious 

 infection frequently occurs to constitute the disease known as 

 navel infection or omphalo-phlebitis. The urachus, too, may re- 

 main open (pervious urachus) or become re-opened a few days 

 after birth through the agency of infection, much as arteries re- 

 open to constitute secondary hemorrhage from infected wounds. 



The Whartonian gelatine, if retained in the cord by means of 

 a ligature, serves the dangerous purpose of a culture medium for 

 bacteria. When the cord is normally ruptured, the Whartonian 

 gelatine quickly oozes from the broken surface, the stump of the 

 cord soon dessicates, the wound occasioned by the rupture 

 becomes hermetically sealed and, from that moment on, infection 

 is excluded. 



