STABLE MANAGEMENT OF SICK AND INJURED. 15 



should be closely observed ; as will be learned in detail later, they are 

 an important guide in determining the physical condition of the 

 animal. 



The normal temperature of the horse in the internal part which 

 is most easily accessible, the rectum, may be estimated at from 99° 

 to 101° F. In ver}'^ young animals the temperature is commonly 

 about 101°, but in very old ones it has been known to be as low as 

 96° F. The temperature of the external parts of the body becomes 

 lower according to their distance from the heart, and liable to much 

 vr.riation from the state of the surrounding atmosphere. Fever is 

 an elevation of temperature. 



The production of animal heat is due to certain chemical and vital 

 changes which are continually taking place in the body ; these changes 

 consist in the absorption of oxygen by the capillaries in the lungs, and 

 the combination of that oxygen with the carbon and hydrogen derived 

 (first) from the disintegration of animal tissues and (second) from cer- 

 tain elements of the food which have not been converted into tissue. 



This combination with oxygen, or oxidation, not only takes place 

 in the blood, which may be looked upon as a fluid tissue, but in the 

 tissue cells also, in all parts of the body, the animal heat being main- 

 tained by the natural changes which are essential to a healthy 

 condition. 



As previously stated, oxygen is absorbed from the air by the capil- 

 laries of the lungs in respiration (breathing). Expired air is found 

 to have lost about 10 per cent of the oxygen contained in pure air, 

 and to have accumulated a like aniount of a combination of carbon 

 and oxygen, called carbonic acid gas. If we imagine the animal 

 breathing and rebreathing the same air, it can be seen that the oxygen, 

 so necessary for the purification of the blood, would soon diminish 

 to a dangerous degree. Hence, we realize the importance of a large 

 supply of air to draw on and the necessity of good ventilation. At 

 each inspiration the horse draws about 250 cubic inches of air into 

 the lungs, and he therefore requires about 2 cubic feet per minute, 

 or 120 per hour. It is customary, in building ordinary stables, to 

 allow 1,600 cubic feet of air space (over twelve hours' supply) for 

 each animal, and to provide means of admitting fresh air without 

 causing drafts. In infirmary stables the allowance is increased to 

 1,900 cubic feet. 



Without good air the blood is imperfectly purified, the vitality of 

 the animal is lessened, he is more susceptible to disease, and will suc- 

 cumb more easily when attacked; consequently horses should never 

 be kept in the vicinity of a marsh, the air from which contains an 

 excess of carbonic acid gas and a diminished supply of the necessary 

 oxygen. 



