239 



In fact, whatever parts the aneurism may reach or subject to its pres- 

 sure, may have their functions suspended or disturbed. When the 

 tumor in the chetst is large we generally find much irregularity in the 

 action of the heart; the superficial veins of the neck are distended, and 

 there is usually dropsical swelling under the breast and of the limbs. 

 There may be a very tr<>ublesorae cough without any evidence of lung 

 affection. Sometimes pulsation of the tumor may be felt at the lower 

 part of the neck where it joins the chest. When ihe aneurism occurs 

 in the posterior aorta no diagnostic symptoms are appreciable; when it 

 occurs in the internal iliac arteries an examination per rectum will re- 

 veal it. 



There is one form of aneurism which is not unfrequeutly overlooked, 

 aff"ecting the anterior mesenteric artery, primarily induced by a worm — 

 the Strongylus armafus. This worm produces an arteritis, with atheroma, 

 degeneration, and dilatation of the mesenteric arteries, associated with 

 thrombus and aneurism. The aneurism gives rise to colic, which ap- 

 pears periodically in a very violent and often persistent type. Ordinary 

 colic remedies have no effect, and after a time the animal succumbs to 

 the disease. In all cases of animals which are habitually subject to 

 colicky attacks, parasitic aneurism of the anterior mesenteric artery 

 may be suspected. 



Fathology. — Aneurisms maybe diff"use or sacculated. The diffuse con- 

 sists in a uniform dilatation of all the coats of an artery, so that it as- 

 sumes the shape of a cylindrical swelling. The wall of the aneurism 

 is atheromatous or calcified ; the middle coat may be atrophied. The 

 sacculated or circumscribed aneurism consists either in a dilatation of 

 the entire circumference of an artery over a short portion of its length, 

 or in a dilatation of only a small portion of one side of the wall. Aneu- 

 rism may become very large; as it increases in size it presses upon and 

 causes the destruction of neighboring tissues. The cavity of the auen- 

 rismal sac is filled with fluid or clotted blood, or with layers of fibrin 

 which adhere closely to its wall. Death is produced usually by the 

 pressure and interference of the aneurism with adjoining organs, or by 

 rupture. In worm aneurism we usually find large thrombi within the 

 aneurismal dilatation of the artery, which sometimes plug the whole 

 vessel or extend into the aorta. Portions of this thrombus or clot may 

 be washed away and produce embolism of a smaller artery. The effect 

 in either case is to produce anaemia of the intestinal canal, serous or 

 bloody exudation in its walls, which leads to paralysis of the intestine 

 and resultant colicky symptoms. 



Treatment. — The only treatment advisable is to extirpate or ligate the 

 tumor above and below. 



RUPTURE OF AN ARTERY. 



Endarteritis, with its subsequent changes in the walls of arteries, is 

 the primary cause of rupture iu the majority of instances. The rupture 



