111_|. Obstruction of the Larger Arteries. 



reappears on the next occasion, unless accidentally paralytic 

 liemoglobinemia has been added, to which horses with throm- 

 bosis of the arteries of the extremities appear to be predisposed. 



General symptoms are also present as a rule. The animal 

 shows great anxiety, the heart action is remarkably excited and 

 accelerated, the respiration is also accelerated and difficult, the 

 mucous membranes show intense injection. Although a general 

 perspiration takes place, the affected extremity remains dry 

 (Humbert, Gal), it feels very cool to the touch (Palat). Fried- 

 berger & Frohner have observed no general symptoms in throm- 

 bosis of the axillary artery, in spite of existing motor disturli- 

 ances. 



Thrombosis may be recognized with absolute certainty, if 

 it is possible on palpation to find firm blood clots or a compress- 

 ing swelling in the related blood vessels. In many cases the 

 hand, which has been introduced into the rectum, may ascertain 

 the presence of the thrombus on palpating the aorta or the 

 larger vessels on the sides of the pelvis ; its presence may also 

 be assumed, owing to the weakness or complete absence of pulsa- 

 tion or owing to a thrill which may be felt. If the thrombosis 

 cannot be found within the pelvis, a total or partial obstruction 

 of the femoral or axillary arteries may be assumed to exist from 

 the fact that the pulse cannot be felt at all or only feebly in the 

 vessels beyond the thrombus, on the metatarsus or metacarpus. 



A partial thrombosis sometimes produces no disease symptoms whatever. 

 For instance a horse with partial thrombosis of the j)osterior aorta covered a 

 distance of 130 km. two days before autopsy (Gratia). 



Glockner has observed difficult deglutition, whistling respiration, and later the 

 symptoms of pulmonary emphysema in thrombosis of the carotid arteries. — Siegen 

 saw epileptiform convulsions in thrombosis of the left carotid and the internal 

 carotid; the convulsions appeared only after the horse had trotted for 20-30 minutes 

 and lasted about 20 minutes. 



Course and Prognosis. In a portion of the cases softening 

 or contraction of attached thrombi occurs, so that the blood 

 paths become more or less opened, or the obstruction persists, 

 but the circulation in the territory concerned is equalized bj^ the 

 collateral circulation which has meanwhile been established. In 

 l)otli cases the affected part of a body may after a certain time 

 (3-6 months) again receive a sufficient supply of blood for the 

 muscles to accomplish even continued and severe work. A com- 

 plete recovery in this meaning of the term is nevertheless very 

 rare, since the supply of blood through the narrowed paths or 

 through the new collateral tracks still remains insufficient, and 

 since the existing thrombosis gives rise to the further produc- 

 tion of fibrin or to embolism, which are followed by relapses and 

 by aggravation of the condition. In exceptional cases throm- 

 bosis of the posterior extremities may be complicated eventually 

 by thrombosis of the brachial artery (Schraml). 



In other cases, an equalization of the circulatoiy disturb- 

 ances does not take place, the function remains permanently im- 



