YENESECTION 699 



blood should not be withdrawn. The total quantity of blood 

 is equal to about 13.5 per cent, of the body weight in horses ; 

 to 2.2 per cent, of the body weight of fat swine ; to 6.6 per 

 cent, of the body weight in dogs, and to 7.7 per cent, of the 

 body weight in man. Large horses or cattle may be bled to 

 the extent of from 4 to 6 qts.; smaller subjects, 2 to 4 qts. ; 

 sheep, ^ to 1 pt. ; dogs, 4 oz. to 1 pt. 



Blood-letting is generally done to animals in the upright 

 position by shaving the hair and cleansing the skin over the 

 jugular vein in the upper part of the neck. The vein is 

 made prominent by pressure below the site of operation, and 

 a fleam, or knife carefully guarded, is plunged into the vein, 

 making a good clean incision. The blood should be quickly 

 withdrawn and carefully measured and the effect on the 

 pulse noted, and the blood-letting maintained until there is 

 noticeable reduction in the vascular tension and other 

 symptoms, for the relief of which venesection is employed. 

 The bleeding is arrested by suturing the lips of the wound 

 and by pressure with a bandage. 



Local Blood-letting J or Scarification, is often useful in 

 relieving tension and pain in locally congested or inflamed 

 tissues, and may even avert death of the part. Further- 

 more, stasis is removed and exudation from the engorged 

 vessels may be prevented, while a fresh supply of arterial 

 blood flows in to reinstate the vital processes. 



Scarification is practiced by making numerous small, 

 parallel incisions into the skin, fascia or other tissues in the 

 long axis of a limb or part. In iuflammation of the perios- 

 teum it is necessary to puncture this membrane. Bleeding 

 is facilitated by warm poulticing, and is arrested by packing 

 the incisions with sterile gauze. 



