358 VETERINARY SURGICAL THERAPEUTICS. 
Tf their etiology is not well known, their pathology is, at least for those 
that affect the vessels of the extremities. Thrombosis being either incom- 
plete or very slow in its development, the increased collateral circulation. 
prevents all accident of gangrene. Besides this, the bloody supply is suf- 
ficient through the muscles when at rest; but if exercise is demanded of: 
the animal, the quantity of blood that they receive is unable to insure thier 
normal functions and then occurs a true impotency of these ischemied. 
muscles. At the time when the conditions of apparition of the lameness. 
are realized, the region, poorly supplied, becomes the seat of an excessive- 
pain ; the aspect of the animal is anxious, the great furictions are accelerated.. 
If the artery can be explored beyond the obstruction, it is found that the- 
pulsations have disappeared ; palpation of the collateral of the canon give 
no longer the pulse. In the entire region where the diseased vessel is. 
distributed, the skin is dry and cold, while it is hot and at times covered. 
_with perspiration in the other parts of the body, when the exercise has been. 
too long. These symptoms, added to this peculiarity, that the lameness. 
occurs after a certain amount of exercise and disappears after rest, are suf-- 
ficient to establish the diagnosis of arterial thrombosis. 
In the thrombosis of the aorta and tts division the clot occupies variable- 
positions: it is found in the lumbar portion of the vessel, at its bifurca- 
tion or in one of its terminal branches. The symptoms vary according to- 
the location or the extent of the obliteration. When this is incomplete, 
either the gait is regular at the beginning of the exercise, or stiffness of the: 
hind quarters, resembling that of sprains of the loins, is observed. More- 
severe symptoms appear after a few minutes of trotting exercise : sometimes. 
it is a more or less complete paraplegia, but as the lesions are always more: 
marked on one side, it is more commonly a marked lameness of the cor-. 
responding member. It is easy to recognize the nature of these accidents. 
‘and distinguish them from those due to sprains of the loins, to muscular- 
lacerations or diseases of thespinal cord. The increased severity of the 
symptoms by exercise, the absence of arterial pulsation or the diminution of. 
their force below the thrombosis and the lowering of the temperature of the: 
extremity suffice to make the diagnosis. 
Thrombosis of the brachial trunk is more rare than that of the aorta. 
Bouley, Schramb, George, Guntherberger, Weinberg, Méller, have re-: 
corded cases of it. The patient of Bouley had regular movements at the: 
beginning of the exercise; after five minutes, he was lame on the left: 
foreleg ; after fifteen minutes, it was impossible for him to rest his foot on. 
_the ground; at the same time his respiration became accelerated and 
_loud, the skin was covered with perspiration, except the lame leg. At 
post-mortem there was found an obliteration of the brachial’ trunk and its. 
divisions (sus-scapular, great posterior muscular, epycondiloid, anterior: 
