MOUNTED INSTRUCTIOM 49 



STABLE HYGIENE 



Ventilation 



The two purposes in ventilation are getting fresh air with its oxygen 

 into a stable, and getting impurities out, and these are equally 

 important. 



Impurities: The common impurities of air, disease germs and their 

 products, carbon dioxide gas, various volatile matters from the lungs, 

 together with the various excretions and the products which result 

 from their chemical decompositions. 



Necessity of Ventilation: To illustrate the effect of poor sanitary 

 conditions, particularly lack of ventilation, it is only necessary to call 

 attention to the common experience of moving an animal affected with 

 a chronic type of glanders or tuberculosis from a well-lighted and 

 well-ventilated stable to one where the conditions are the opposite. 

 Under the latter conditions there is rapid development of a disease 

 which has been mild. Sick animals especially need free ventilation. 

 This is particularly true in certain diseases, e. g. tetanus and diseases 

 of the lungs, and respiratory tract. A moderately warm stable in a 

 cold climate is not objectionable, providing sanitary conditions, such 

 as abundant air, sunlight, good food and water, are provided. But 

 making a stable warm and tight may very easily establish an ideal 

 place for the propagation of germs and the spread of disease. 



Natural Forces: The factors that operate in natural ventilation. are : 



1. The force of the wind. 



2. Weight of air, as varied by its temperature. 



3. Dift'usion of gases in obedience to a natural law. 



Wind : The force of the wind is probably the most important one 

 of these factors, and must always be taken into consideration in plan- 

 ning ventilation. It is, of course, irregular, but variations can be 

 made in the ventilation facilities to compensate for this. A funda- 

 mental point in using this factor is to see that the incoming air does 

 not pass over or through any contaminating course, over a manure 

 pile, or strike the body of the horse. 



Temperature and Weight: The second factor, difference in weight 

 between the lighter warm and heavier cold air, is not so important in 

 natural as in artificial ventilation, and yet it is a factor of considerable 

 importance. The heat which warms the air in the lower levels is that 

 which comes from the bodies of confined animals as it is radiated 

 from the surface or warmed in passing through the lungs. 



Diffusion of Gases: Carbonic gas is considerably heavier than air, 

 and the lower levels usually contain a slightly higher percentage than 

 the higher ones in a stable, but the difference is not so great as one 

 would suppose, on account of the diffusion which takes place in 

 response to the law of diffusion of gases — which operates independ- 

 ently of relative weights. This force is so strong in its action that 

 some diffusion takes place through unpainted lumber and through ordi- 



