CHAPTER XX 

 NON-COMMUNICABLE DISEASES 



Non-communicable diseases include all affections that are 

 not transmissible by direct or indirect contact from one animal 

 to another. In general they are traceable to a disordered condi- 

 tion of metabolism which results in physiologic disturbances. 

 Those that are due to digestive disorders have been discussed in 

 Chapter XVI. In this chapter will be described the more com- 

 mon ones that result from mechanical interference with physio- 

 logic processes — e. g., pneumonia and heaves, and those that arise 

 from the production of substances which act as poisons to and 

 interfere chemically with normal metaboUsm — e. g., azoturia and 

 forage-poisoning. 



The course of this class of diseases varies widely and their 

 symptoms are indefinite. As they often resemble certain com- 

 municable diseases in their more general manifestations, it may 

 be difficult to make a differential diagnosis. 



PNEUMONIA 



Pneumonia means any infiammation of the lungs. It is accom- 

 panied by an exudation of liquid into the minute air-sacs, and 

 later solid matter forms. This reduces the capacity of the lungs 

 to deliver oxygen to the blood and remove carbon dioxid and the 

 animal shows difficulty in breathing. 



With our present knowledge it is impossible to attribute pneu- 

 monia of the horse to a specific micro-organism, although it seems 

 probable that most cases, if not directly due to the presence of 

 micro-organisms, are sooner or later infected with them. Direct 

 irritation from foreign bodies like lung-worms, smoke, dust, drench- 

 ing through the nose, and aspiration of food are exciting causes. 

 Exposure to cold is known to play an important part in causing 

 pneumonia. 



At the outset the symptoms are not marked, and are either 

 completely overlooked by the attendant or not regarded as indic- 



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