CIRCULAR UlSTURISANCIiS. 



113 



Hemorrhage is the escape of blood from a vessel, (capillary, 

 vein, artery or heart.) 



Etiology. — Some animals are predisposed to hemorrhage 

 (hemophilia). Hemorrhagic diathesis or hemophilia is an in- 

 herited ci->ndition in which there is little or no ten(lenc_v for 

 coagulation of blood. The cause of this condition is the ab- 

 sence of some blood constituent essential td cuagulation 

 or rupture of vessel wall, resulting from diseased vessels 

 as ulceration, thus producing hemorrhage 1)}- diahrosi.';. or in 



Fig 7,s. — I'etecbial hemorrhage, Kidne.v hog cholera lesion. 



a. Hemorrhagic area. c. Glomerulus engorKc'd wiUr blmid. 



b Normal kidnej- tubUle. 



creased pressure and traumatism, thus producing hemorrhage 

 by rlic.vis. The permeability of the vessel walls may l)e suffi- 

 ciently increased by pressure or disease so that hemorrhage 

 takes place by dia[>cdcsis. The escaped blood, i. e., the ex- 

 travasate, may flow upon the surface of the skin, serous or 

 mucous membranes, or into the tissues. 



TISSUE HEMORRHAGES may vary greatly in amount and are 

 designated by the following terms, petechia, ecchymosis, sug- 

 o-ilation, effusion, infarction and hematoma. 



Prtechiae are small sharply defined hemorrhagic ]iomts and are 

 probably caused by bacterial products in the blood. 



