516 GENERAL THERAPEUTIC MEASURES 



tion to the right heart. Moderate blood-letting is occasionally useful in 

 severe cases of acute pleuritis^ laminitis, lymphangitis and urticaria in 

 plethoric horses. 



Finally, in various toxemias, blood-letting drains away both the 

 blood and its contained poison. The mass of blood removed may be 

 advantageously replaced by injection of normal salt solution into a vein 

 or under the skin. This method is not in prevalent use in veterinary 

 medicine, but is applied with notable success in human practice. Every 

 veterinary practitioner should be competent to bleed an animal. An 

 amount greater than 1/5 of the total quantity of 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 withdrawn.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 sterilizing 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 

 transversely 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 should be quickly withdrawn and carefully measured and the effect on 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, or Scarification, is often useful in relieving ten- 

 sion 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 in- 

 cisions 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. 



IlfDICATIOlsrS. 



Lampas. Mastitis. 



Glossitis. Laminitis. 



Periostitis. (To secure blood for microscopic ex- 



Cellulitis. amination.) 



Conjunctivitis. 



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 condi- 

 tions whenever there is great swelling, pain and tension in the affected 

 parts, and not otherwise. 



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