66 GENERAL THERAPEUTICS FOR VETERINARIANS 



may be precipitated as a calcium-albumin compound through the 

 cooperation of three factors: 1. Fibrin ferment (a product of the 

 decomposition of white blood-cells). 2. The fibrinogens. 3. 

 The fibrinoplastic substances: fibrinogen and paraglobulin. 



Therapeutic Methods. — ^Wounds and the consequent hemor- 

 rhage are the conditions which most frequently affect the blood- 

 vessels, and for this reason the method of arresting hemorrhage 

 will first be considered. Other therapeutic methods are concerned 

 with the contraction and dilation of the blood-vessels (see also the 

 antiphlogistic and resorbent methods). 



1. METHODS OF ARRESTING HEMORRHAGE 



Spontaneous Arrest of Hemorrhage. — ^By this is understood 

 the cessation of bleeding as a result of a natural process, in con- 

 tradistinction to the artificial arrest of hemorrhage by therapeutic 

 measures. It is especially observed in capillary and parenchy- 

 matous hemorrhage, and also occurs when small arteries and veins 

 are wounded. It is due principally to the coagulation of the blood, 

 but retraction of the vessel wall and narrowing of the lumen of the 

 vessel are also important factors. The coagulation of the blood 

 forms a thrombus, which closes the opening in the vessel and some- 

 times extends into the interior. As the blood-pressure is very low 

 in the capillaries and small veins, the formation of thrombi and the 

 resulting arrest of hemorrhage can occur very quickly. But in 

 large vessels, especially arteries, thrombi are not formed at all or 

 only when the heart has become weak and the blood-pressure has 

 been considerably lowered by severe hemorrhage, so that the 

 coagulated blood is not washed away by the outpouring blood. 

 In severe hemorrhage the blood, in an effort to rehabilitate itself, 

 takes up numerous white blood-corpuscles, which increase its 

 coagulability and thus assist in the spontaneous arrest of bleeding. 

 This is the explanation of the fact, established experimentally,that 

 stallions castrated without any precautions against bleeding do not 

 die from loss of blood. Generally, however, not more than one- 

 third of the total quantity of blood can be lost without causing 

 fatal cardiac and cerebral paralysis. The blood regenerates itself 



