DECREASING THE VOLUME OF BLOOD 109 



MEASURES FOR DECREASING THE VOLUME OF BLOOD. 

 VENESECTION, PHLEBOTOMY, BLEEDING 



Bleeding is one of the oldest therapeutic measures and was fre- 

 quently employed in the older systems of medicine, but has been 

 almost discarded. A careful examination of its former uses has 

 shown that in most of these it was not only useless but in many cases 

 decidedly harmful, particularly so in its use in febrile and inflam- 

 matory conditions in general. On the other hand, there are some 

 cases in horse and cattle practice in which it may be of decided 

 benefit. 



Venesection is the process of removing blood by opening a vein. 

 The jugular vein is the one most used in large animal practice, but in 

 the days when bleeding was the regular custom it was a common 

 practice to bleed from the palatine veins and arteries, although only 

 comparatively small amounts of blood were drawn from these 

 sources. The usual method of bleeding was to raise the jug^^lar with 

 the finger or tourniquet, and then open it with a bistury or phleme 

 and allow the desired quantity to escape. The bleeding was then 

 stopped by a skin suture or pin suture through the skin retained by 

 a figure eight string or horse hair. See works on surgery. 



The most marked effect upon the body of the removal of large 

 amounts of blood (5 to 10 quarts in horses and cattle) is the with- 

 drawal of a large amount of water, which agrees very closely to the 

 effects of diaphoretics, diuretics, sialogogues and laxative drugs. 

 FoUovdng this, there is a tendency for the blood to regain its normal 

 volume as quickly as possible by taking up the fluids at its disposal, 

 lymph, fluid exudates, causing a temporary hydremia. This action 

 is the basis for the principal use of blood letting. Blood pressure 

 also usually falls. In addition to the above, there is a derivation of 

 the blood from the internal organs, and the more rapidly the blood 

 is withdrawn from the veins the more promptly this action occurs. 



The General Uses of Blood-Letting Are: 



1. In conditions of high blood pressure. 



a. In inflammation of the brain; in the early stages so long as 

 the symptoms of cerebral congestion are pronounced, such as, conges- 

 tion of the visible mucous membranes of the head, increased temper- 

 ature of the cranium, strong pulsation of the arteries of the head and 

 symptoms of excitement. 



b. Laminitis. According to Frohner, free bleeding as early as 

 possible, together with the use of axecoline is the best treatment for 

 this disease. 



c. High blood pressure of eclampsia and uremia in human medi- 

 cine. 



2. In conditions of venous engorgement with heart weakness, es- 

 pecially in edema of the lungs. 



