346 Veterinary Medicine. 



blood clot formed in the veins or heart and carried on with the 

 current until it reaches an artery too small to admit it (embolism). 



The inflammation may be confined to a limited space as when 

 an artery is bruised, stretched so as to tear through its inner 

 coats, or interrupted b}' a ligature. It may on the other hand be 

 diffused over a greater extent of the vessel, and in .some cases 

 two inflamed portions are separated by intervals of sound artery. 



Anatomical features of the inflamed artery. In active in- 

 flammation of the internal coats of an artery, it contains blood 

 clots, and if the inflamed surface is not very limited in extent the 

 vessel is completely plugged and the clot forms up to its nearest 

 transverse branch on the cardiac side, precisely as if the artery 

 had been tied. The resulting clot is sometimes tubular, so that 

 an impaired circulation is still carried on. The clot varies in 

 length according to the extent of vessel inflamed, or the distance 

 from the inflamed spot to the nearest diverging branch. The clot 

 is usually fusiform in outline and is firmly attached throughout 

 more or less of its diameter, and occasionally .so firmly that it is 

 all but inseparable from the serous membrane. The narrowed 

 ends of the clot mostly float free in the liquid blood and portions 

 from the end most distant from the heart will sometimes get de- 

 tached, and by blocking up smaller arteries give rise to new 

 centres of disease. This is a true instance of embolism or 

 plugging. 



The clot has nearly always a grayish or yellowi.sh white color 

 in the larger ves.sels, such as the posterior aorta, and an uniform 

 pink or red streaked with yellow in the small. It is possessed of 

 great firmness and elasticity. That portion of the surface which 

 was not attached to the arterial walls, during life, is clear, smooth 

 and glistening, while the portion which adhered to these walls is 

 rough, irregular, and broken into shreds. It is usually composed 

 of concentric layers .showing its mode of formation. 



Clots of this kind analyzed by M. M. La.ssaigne and Clement 

 were composed of water 74 parts ; fibrine and albumen 25 parts ; 

 and alkaline salts i part. 



The vessels filled by these clots are very irregular in their out- 

 line being thick and bulging at one point and thin and constricted 

 at another. The outer coat is rarely the seat of morbid change, 

 though it sometimes shows branching redness and thickening 

 from exuded lymph. The internal coat where the clot was 



