llD VETERINARY PATHOLOGY. 



From V's to Yi of the volume of the blood in the body may be 

 withdrawn at once and the animal recover. Hemorrhage from 

 a small vessel has little effect upon the welfare of the body for 

 the quantity lost is immediately restored from the lymph and 

 other fluids of the body. Thus there may be a constant hem- 

 orrhage from the digital artery of the horse for twenty-four 

 hours without injurious consequences. 



A sudden large loss of blood diminishes blood pressure and 

 this results in imperfect action uf the heart valves. The blood 

 is churned back and forth, becomes mixed with air and this 

 frothy mass accumulates beneath the \alves and prevents their 

 closure. 



Hemorrhage is serious when it occurs in the more delicate 

 or the more highly organized tissues. Thus the amount of 

 extravasate into the cerebrum may be very small and yet pro- 

 duce sufficient disturbance to destroy life, while the same 

 amount of extravasate into the muscles of the thigh, forearm, 

 etc., would probably not be observed. 



The extravasation of blood into one of the body cavities, as 

 the pleural or peritoneal cavity, will be partially absorbed as 

 entire blood Ijefore it beecomes coagulated, the remaining un- 

 absorbed portion will be in part disintegrated and carried out 

 by the leucoc\-tes and the remaining portion will finallv be- 

 come organized and remain as a mass of fibrous tissue. If the 

 loss of blood is not sufficientlv large to materialh- diminish the 

 blood pressure and the extravasate remains free from infection 

 there will be very little inconvenience from the hemorrhage; 

 but if the extravasate becomes infected the outcome will be 

 more serious. If the extravasate is into some important tissue 

 the secondarv changes will be of more consequence than when 

 in the body cavities. 



There is a natural tendencv for self arrest of hemorrhage, 

 because, 1st, blood pressure is diminished during hemorrhage 

 and thus coagulation is favored; "..'nd, the endothelium of the 

 injured vessels becomes roughened and thus thrombic forma- 

 tion is favored ; and 3rd, fibrinogen is liberated from vascular 

 endothelium and thus the coagulation of the blood is favored. 



