CHAPTER XII. 



THHOMBOSIS OF THE POSTERIOR AORTA 

 AND ITS BRANCHES. 



History. — An intermittent lameness of more or less 

 severity when engaged in active work, disappearing while 

 resting, and reappearing on brisk exercise. 



Inspection. — In the standing posture, and before any 

 active exercise has been taken, nothing abnormal is seen, 

 but as soon as the animal is given a good trot of a few to 

 several hundred yards, supporting-leg lameness or swinging- 

 leg lameness, depending on the vessels obstructed, promptly 

 sets in. 



Palpation. — Now and then the lame leg is colder than 

 than the other one, and rectal examination of the aorta or 

 its branches locates the obstructed vessel. 



(«) FEMORAL AETERY. 



Shortened and retarded forward stride combined with 

 dragging of the leg. (Swinging-leg lameness.) 



(h) ILIAC ARTERY. 



Supporting-leg lameness, with collapse of the leg when an 

 attempt is made to sustain weight. When both arteries are 

 obstructed the hind legs sway to and fro. Should exercise 

 be continued, the hind legs rapidl}' become powerless, and 

 the animals falls. In such cases, as well as in thrombosis 

 of the posterior aorta, inability to sustain any weight, even 

 when standing, is a consequence. These severe cases are 

 frequently accompanied by violent beating of the heart, 

 difficult respiration and cramps in the muscles of the hind 

 leg. The animal may sweat profusely, yet the lame leg 

 remains dry. 



