218 THE VETERINARY DOCTOR. 
4 
by closing doors, windows, and ventilators, thus keeping the animal ina 
temperature warmer than that to which he has been accustomed, and in an 
atmosphere made impure by noxious gases and a deficiency of oxygen. 
Such treatment will sooner give a horse a cold than an opposite one, for 
he may be turned out of a warm stable to grass with little or no injury, 
since the loss of heat by extreme cold will be repaired by internal combus- 
tion, the oxygen from the cold air acting on the carbon given off from the 
lungs, and thus producing carbonic acid, the chief source of animal heat. 
Cool air stimulates and invigorates the body, rendering it less liable to dis- 
ease; fot air is weakening, for the external temperature being so little be- 
low the internal, heat is not required, and a sufficient quantity of oxygen is 
not breathed to properly assimilate the large amount of nutritious food 
‘still given, which now tends to render the blood impure by excess of car- 
bon, and the body more liable to disease. Cool air increases the appetite 
by bracing the muscular fibers, especially those of the stomach. Hot air 
deranges the liver and organs of digestion. When the temperature is mod- 
erate and oxygen is in excess, the carbon is mainly carried off by the lungs; 
but if the external heat approaches that of the internal, the carbon, instead 
of being removed by the lungs and passed off as carbonic gas, is left to be 
borne off by the liver; and thus the liver and digestive organs become de- 
ranged. We therefore see how important it is to keep our stables cool, 
and at the same time to avoid cold currents of air. The most appropriate 
temperature is sixty degrees, and this we should endeavor to maintain dur- 
ing both summer and winter, even if the surface of the body must be kept, 
warm by a moderate amount of clothing. 
Impure air is a much more fruitful source of disease than hot air; 
hence the importance of keeping the stable thoroughly clean. The air 
which has been breathed, the moisture from sweats, the urine and dung, 
are all very poisonous to the horse. The first two can be easily removed 
by ventilation. The dung should be frequently cleared away, before the 
‘horse has trodden it or the bedding is befouled. Diseased feet as well as 
poisonous air often result from rotted dung. The urine should be carefully 
taken away by drains before time is afforded for the rising of the odors of 
ammonia, which are very hurtful to the health of the animal. 
From what has been said above it is clear that a special regard should 
be had to ventilation, Pure air consists of eighty parts of oxygen and 
twenty parts of nitrogen. Any influence which considerably disturbs this 
proportion proves injurious to the health of the horse. Pure blood and 
good health depend upon a liberal supply of oxygen. If we open an artery 
and immediately examine the blood, we will find it to be a bright-scarlet 
color, coming just from the lungs where it has been in contact with air 
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