98 EX AMI N A TION OF HORSES 



of the remaining condition. This being so, exercise, 

 which will disperse the one — at least for a time — will 

 aggravate the other; consequently, you have the horse 

 thoroughly well exercised, and if the parts get too hot 

 and swollen you reject him as unsound. In old chronic 

 conditions, where over-heat is not induced in these so- 

 called "wind galls" and "thoropins," you have to see 

 that they do not produce mechanical impediment. 



General oedema of the legs (swelled legs) is a very 

 grave unsoundness while it lasts, inasmuch as it denotes 

 a deteriorated condition of the most important tissue of 

 the body — the blood. While it lasts a horse is quite as 

 unsound as a horse suffering from a blood disease. AVe 

 naturally look for this disease in the autumn, when the 

 blood is loaded with debris, at the time when the system 

 is undergoing observable changes. Impure blood de- 

 velops dropsy, with its ghastly train of evils, by lessening 

 arterial tension. It does so in this way : — 



1. The heart walls, fed with impure blood, contract 

 more feebly. 



2. Feeble heart contraction lessens aortic distension, 



3. Lessened aortic distension 



4. Lessens aortic recoil (the propelHng power of the 

 coronary arteries), which 



5. Lessens the coronary circulation, and so the heart 

 walls become weakened for want of a due amount, and 

 proper quality, of blood, and become too weak tb 

 contract thoroughly upon their contents. They never 

 fairly empty themselves ; so that the right heart, never 



