29G DISEASES OF HORSES. 



est exciting cause, or siuldon exposure to weather checken 

 perspiration, or the like, may cause a serious iudisposifion, 

 tliat, under a more favcurable state of the horse's consti- 

 tution, might probably have passed over without leaving 

 any serious proof of its existence. 



Predisposition to disease is, then, that liability of the 

 constitution to an attack of illness, which care and atten- 

 tion will often prevent; but which neglect or bad grooming 

 At once induces or increases. 



We have before noticed, in our remarks on the ventil- 

 lation of the stable, that pure dry air is essential to a 

 healthy state of the blood ; we need scarcely add that 

 good n.ourishing food is equally essential to the well-being 

 of the animal ; to understand this properly, a few words 

 on the digestive powers of the horse will not be inappro- 

 priate. 



The food taken by the horse is gathered up by his lips, 

 and being cut by the action of the front teeth, is conveyed 

 thence to the grinders, by which it is thoroughly masticated. 

 or chewed; it is then, by the united action of the tongue 

 and other muscles, conducted to the gullet, from whence 

 it descends into the stomach. Here it is acted upon by a 

 powerful solvent, provided by nature for the purpose of 

 accelerating the digestive operation, called the gastric juice, 

 and reduced to a'pulpy mass, termed chyme; this mass, 

 yet but imperfectly digested, is then propelled into the first 

 bowel, where other intestinal juices commingle with it, 

 and perfect the digestive process ; it is now termed chyle ; 

 and it is in a state ready for combining with the blood. — 

 The chyle now enters the small intestines, and is conveyed, 

 by a peculiar motion of the bowels, to certain minute ori- 

 fices, called absorbent vessels : in this part of the process 

 the pure chyle, now a milk-like fluid, is absorbed by these 

 vessels ; the other portion of the food eaten by the animal, 

 the excrementitious part, having had all the nourishment 

 exti acted in the course of the digestive process, is propelled 

 by the same peculiar moticm of the bowels, previously 

 noticed, along the whole extent of tbe intestinal canal, or 

 gut, and ultimately expelled the body. — The pure chyle 

 .s conveyed, by the absorbent vessels, into a large receiv- 

 ing tube, called the thoratic duct, from which it is received 

 by a vein near the heart, and taken t'^ence to the heart 



