2 86 DISEASES OF THE DOMESTIC ANIMALS 



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 posi- 

 tion by clipping the hair and painting the skin over the jugular vein 

 with tincture of iodine 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 The blood should be quickly withdrawn and care- 

 fully 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, or Scarification, is often useful in relieving 

 tension and pain in locally congested or inflamed tissues, and may 

 even avert death of the part. Furthermore, 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 inflammation of the periosteum it is necessary to 

 puncture this membrane. Bleeding is facilitated by warm poulticing, 

 and is arrested by packing the incisions with sterile gauze. 



Indications. — Lampas, Glossitis, Periostitis, Cellulitis, Con- 

 junctivitis, Mastitis, Laminitis (to secure blood for microscopic 

 examination). 



Sometimes the veins leading from an inflamed area are opened, 

 thus securing local abstraction of blood; e. g., the digital veins in 

 laminitis; the milk veins in mammitis. 



Scarification, or puncture, is indicated in the above-mentioned 



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