THROMBOSIS OF THE BRANCHES OF THE AORTA. 485 



Pathological anatomy. Thrombi are relatively frequent in 

 the iliac arteries, they are uncommon ou the obturator, still more 

 rare on the axillary and humeral, and quite exceptional on the 

 lumbar arteries.^ In cases of thrombosis of the aorta, the end of 

 this and the opening of its divisions are dilated, the walls of its 

 canals are thickened, affected with atheromatous degeneration, the 

 intima looks suspicious, has undergone fatty degeneration, or is 

 calcified, or partially destroyed, ulcerated. Inside of it we find a 

 hard, stratified and organized clot, which is ordinarily of a grayish- 

 white color, and obstructs the lumen of the bloodvessel, which is 

 often reduced to a narrow canal ; this thrombus frequently extends 

 more or less forward iuto the aorta and backward into its divisions; 

 it is sometimes mounted on the spur of the internal iliac arteries; in 

 some cases one of these is completely obstructed. With this throm- 

 bus we may find a sort of connecting lesion, a compensatory cardiac 

 hypertrophy. When the clot is softened, emboli are formed in the 

 arterial divisions of the posterior members. 



Symptoms. Arterial thrombi generally do not determine any 

 symptoms during rest ; but when the animals are exercised, mounted, 

 hitched up, or led, within a certain time we observe particular and 

 characteristic symptoms. 



1. In thrombus of the femoral artery, which is common in the 

 horse, very rare in the ox (Fordie), we observe from the start a 

 certain constraint in the functional movements of the posterior 

 member, and a weakness which grows more and more marked. 

 After a short exercise the gait becomes embarrassed, the toe of the 

 diseased member is dragged on the ground, the animals tremble, 

 stumble, fall, remain down for a few moments, and manifest intense 

 agitation ; the respiratory movements are very accelerated, the 

 beatings of the heart are precipitate and violent, the visible mucous 

 membranes are much injected ; the body is covered with perspira- 

 tion ; the temperature of the lame extremity is generally lower than 

 that of the other parts of the body ; the pulsations are very often 

 wanting in the tibial and collateral arteries of the canon. The 

 animals rise within a few minutes and come gradually back to a 

 normal state. If we explore the thrombosed vessels by rectal ex- 

 amination, we find these dilated, thickened, rigid, and filled with a 

 hard elongated body ; in most cases we only perceive pulsations at 

 this point. Thrombosis of the peripheric veins sometimes com- 



^ Hahn { communicated). 



