DISEASES OP HEAKT, BLOOD VESSELS, AND LYMPHATICS. 267 



plicable, pressure may be applied by tight bandaging. As a sec- 

 ondary result of rupture of an artery we may have formation of 

 abscess, gangrene of a part, etc. 



Treatment. — When rupture of a deep-seated artery is suspected, 

 large doses of fluid extract of ergot may be given to produce con- 

 traction of the blood vessels. Tannin and iron are also useful. The 

 animal should be allowed to have as much water as he desires. After- 

 wards stimulants and nourishing feed are indicated. 



THROMBUS AND EMBOLISM. 



By thrombosis is generally understood the partial or complete clo- 

 sure of a vessel by a morbid product developed at the site of the 

 obstruction. The coagulum, which is usually fibrinous, is known as 

 a thrombus. The term " embolism " designates an obstruction caused 

 by any body detached and transported from the interior of the heart 

 or of some vessel. Thrombi occur as the result of an injury to the 

 wall of the vessel or may follow its compression or dilatation; they 

 may result from some alteration of the wall of the vessel by disease 

 or by the retardation of the circulation. These formations may 

 occur during life, in the heart, arteries, veins, or in the portal system. 

 When a portion of fibrin coagulates in one of the arteries and is 

 carried along by the circulation, it will be arrested, of course, in the 

 capillaries, if not before; when in the veins, it may not be stopped 

 until it reaches the lungs; and when in the portal system the capil- 

 laries of the liver will prevent its further progress. The formation 

 of thrombi may act primarily' by causing partial or complete obstruc- 

 tion, and, secondarily, either by larger or smaller fragments becom- 

 ing detached from their end and by being carried along by the 

 circulation of the blood to remote vessels, embolism ; or by the coagu- 

 lum becoming softened and converted into pus, constituting sup- 

 purative phlebitis. These substances occur most frequently in those 

 affections characterized by great exhaustion or debility, such as 

 pneumonia, purpura hemorrhagica, endocarditis, phlebitis, puerperal 

 fever, hemorrhages, etc. These concretions may form suddenly and 

 produce instantaneous death by retarding the blood current, or they 

 may arise gradually, in which case the thrombi may be organized and 

 attached to the walls of the heart, or they may soften, and frag- 

 ments of them (emboli) may be carried away. The small, wartlike 

 excrescences occurring sometimes in endocarditis may occasionally 

 form a foundation on which a thrombi may develop. 



Symptoms. — When heart clot, or thrombus, exists in the right side, 

 the return of blood from the body and the aeration in the lungs is 

 impeded, and if death occurs, it is owing to syncope rather than to 

 strangulation in pulmonary respiration. There will be hurried and 



