98 EXAMINATION OF HORSES 
of the remaining condition. This being so, exetcise, 
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 cedema 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. We- 
naturally look for this disease in the autumn, when the 
blood is loaded with débris, at the time when the system 
is undergoing. observable changes. /mpure blood de- 
velops dvopsy, with its ghastly train of evils, by essening' 
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 propelling 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 to 
contract thoroughly upon their contents. They never 
fairly empty themselves; so that the right heart, never 
