DISEASES OF HEART, BLOOD VESSELS, AND LYMPHATICS. 83 



ture, it is necessary to have artery forceps (tweezers or small pincers 

 may suffice) by which to draw out the artery in order to tie the string 

 around it. To grasp the vessel it may be necessary to sponge the 

 blood from the wound so that the end will be exposed. In case the 

 end of the bleeding artery has retracted, a sharp-pointed hook, called 

 a tenaculum, is used to draw it out far enough to tie. The ligature 

 should be drawn tightly, so that the middle and internal coats will be 

 cut through. 



Another method of checking hemorrhage is called torsion. It con- 

 sists in catching the end of the bleeding vessel, drawing it out a little, 

 and then twisting it around a few times with the forceps, which lacer- 

 ates the internal coats so that a check is effected. This is very effect- 

 ual in small vessels, and is to be preferred to ligatures, because it 

 leaves no foreign body in the wound. A needle or pin may be stuck 

 through the edges of a wound, and a string passed around between 

 the free ends and the skin (PI. XXVIII, fig. 10), or it may be passed 

 around in the form of a figure 8, as is often done in the operation of 

 bleeding from the jugular vein. 



ANEURISM. 



A circumscribed dilation of an artery, constituting a tumor which 

 pulsates synchronously with the beats of the heart, is called aneurism. 

 It is due to disease and rupture of one or two of the arterial coats. 

 The true aneurism communicates with the interior of the artery and 

 contains coagulated blood. They are so deeply seated in cattle that 

 treatment is out of the question. These abnormalities are due to 

 severe exertion, to old age, to fatty or calcareous degeneration, or to 

 parasites in the blood vessels. Death is sudden when due to the rup- 

 ture of an aneurism of a large artery, owing to internal hemorrhage. 

 Sometimes spontaneous recovery occurs. As a rule no symptoms are 

 caused in cattle by the presence of deep-seated aneurisms, and their 

 presence is not suspected until after death. 



A false aneurism results from blood escaping from a wounded 

 artery into the adjacent tissue, where it clots, and the wound, remain- 

 ing open in the artery, causes pulsation in the tumor. 



THROMBOSIS (OBSTRUCTION) OF THE ARTERIES. 



Arteries become obstructed as a result of wounds and other injuries 

 to them, as those resulting from the formation of an abscess or the 

 extension of inflanunation from surrounding structures to the coats 

 of an artery. Arteries are also obstructed by the breaking off of 

 particles of a plug or clot, partly obstructing the aorta or other large 

 artery. These small pieces (emboli) are floated to an artery that is 

 too small to permit them to pass and are there securely held, pro- 



