Pathogenesis, Symptoms. 1113 



supply all tissues of tlie body part in question with the nutri- 

 tional substances necessary for life, and which sometimes even 

 enables in muscles to accomplish a certain degree of work. If, 

 however, the animal accomplishes prolonged and severe mus- 

 cular labor, the deficiency in oxygen causes an insufficient oxida- 

 tion and therefore the development of insufficient force, and also 

 a transitory accumulation of products of metabolism in the 

 muscle, especially lactic acid and carbonic acid, which lead to a 

 more rapid fatigue of the muscle. When the exercise is inter- 

 rupted, the products of fatigue are gradually eliminated from 

 the muscle, the feeling of fatigue and the disturbance in func- 

 tion are abated, but reappear on renewed prolonged muscular 

 exertion. 



Symptoms. The form and the intensity of motor disturb- 

 ances depend upon the arteries which are obstructed and upon 

 the degree of occlusion. In the rather rare thrombosis of the 

 posterior portion of the aorta the trotting or galloping horse 

 begins, after a variable time, to become uncertain in the hind- 

 quarter, it staggers, the feet are raised less high, and soon it can 

 no longer move at all, remaining standing, bathed in perspira- 

 tion and trembling. If urged further, it finally collapses and 

 falls to the ground. While lying on the ground the animal grad- 

 ually becomes calmed ; it arises, after a time, of its own accord 

 and may move at a walk. 



In thrombosis of aortic branches, especially the pelvic or 

 femoral arteries, the motor disturbance commences in a similar 

 manner, but is limited to one of the posterior extremities. After 

 a certain time, which may be only a few minutes, the horse raises 

 the foot less high, it cannot move it very certainly, may interfere 

 occasionally against the other foot ; it hangs its head and if pos- 

 sible bears the weight of the body upon the front feet ; soon the 

 joints are bent less and less, the hoof scraping the ground at 

 each step, and finally the affected foot gives out, the animal fall- 

 ing upon the diseased side of the body on being urged further. 

 In bilateral thrombosis of the femoral artery the motor disturb- 

 ances correspond as a whole with those of thrombosis of the 

 abdominal artery, although the uncertainty in the sacral region 

 is less striking. 



Thrombosis of the axillary and brachial arteries leads to 

 similar disturbances in motion in the one fore foot. Here also 

 a gradually increasing muscular weakness becomes perceptible, 

 the horse stumbling on the fore foot, knocking it against impedi- 

 ments and scraping the ground with the hoof, until the foot 

 commences to tremble violently and is finally paralyzed. 



Complete occlusion of the pelvic arteries causes paralysis 

 of the sacrum, the tail, the bladder, and of the rectum ; a partial 

 thrombosis gives rise to motor disturbances, which occur only 

 on motion and is similar to sacral paralysis. 



The paralysis disappears after a certain period of rest but 



