COURSE OP NORMAL BIRTH 77 



THE NEWLY BORN ANIMAL. 



As soon as the calf is born normally, severing of the umbili- 

 cal cord takes place without intervention on the part of the 

 obstetrician. In bovines, the navel string, being of little 

 resistance, tears easily; before the fore-quarters of the calf 

 pass the vulva, connection between mother and the young has 

 already ceased to exist. 



Although the rupturing of the umbilical cord usually 

 gives us little concern, it is nevertheless a very important 

 point. 



I shall explain this further and describe how the umbilical 

 cord tears and what the consequences are when the circula- 

 tion stops to run through it. 



Rupture of the umbilical cord of the calf differs from that 

 of other animals. At birth of the calf the umbilical cord is 

 rendered so tense that it ruptures. The umbilical vein tears 

 in the umbilicus, while the umbilical artery, after being severed, 

 retracts into the subperitoneal tissue. Therefore, this rupture 

 in tiie calf takes place within the abdominal cavity. No hemor- 

 rhage follows rupture of the umbilical arteries on account of 

 the energetic contractions of the muscularis of the arteries, 

 which comprises the whole length of the umbilical arteries. 

 After parturition the foetal and membraneous portion of the 

 artery is anaemic. The peripheral piece of the umbilical vein 

 at the site of rupture is cone-pointed and full of blood, while 

 the intra-abdominal portion of the vein often contains a co.igu- 

 lum (Kehrer). 



After circixlation through the umbilical cord ceases, import- 

 ant changes occur in the calf : primarily, respiration. It has 

 been mentioned previously that by asphyxia of the foetus intra- 

 uterine respiration is called forth. Inspiratory movements may 

 be provoked in the foetus by compressing the umbilical cord. 



It is a fact that the young animal begins to breathe as soon 

 as the cord tears. The thorax expands and the first respiratory 

 movement is a slow inspiration, accompanied by rales caused 

 by the presence of amniotic fluid in the respiratory tract. The 



