238 A MANUAL OF VETERINARY PHYSIOLOGY 



physiology, and we feel that the physiological aspect of digestive 

 disorders has not yet received adequate attention. We must bear 

 in mind that the whole length of the digestive tract is a chemical 

 laboratory concerned in the analysis of food-stuffs, isolating and 

 retaining those which are of use, getting rid of those which are use- 

 less, and rendering harmless those substances capable of acting in- 

 juriously. Not only is it a laboratory where the above analytical 

 operations are carried out, but it is also a factory where the chemical 

 reagents necessary for this process are prepared beforehand. So 

 thoroughly is the analysis performed, that the most complex bodies 

 are broken down into the simplest products. Can it be wondered at 

 that the chemical processes may sometimes fail, and disorder result ? 



We see a faithful reflex of the laboratory processes in the disorders 

 of the canal, the diarrhoea which is full of beneficence, impaction 

 which indicates a loss of muscular power and physical alteration 

 of the contents, acute tympany which announces active fermenta- 

 tion, rupture which indicates the strain on the walls of the apparatus ; 

 these, and others too numerous to be dealt with, and which no mere 

 mention explains, give some idea of the penalty paid by horses for 

 the doubtful privilege of domestication. The term ' digestion of a 

 horse ' has been framed in absolute ignorance of the real facts. 

 There is no animal in which these organs are more readily disturbed, 

 and none in which they are the subject of such acutely painful and 

 mortal lesions. 



The ruminant, from the peculiarity of its physiological arrange- 

 ment, is far more liable to stomach than intestinal trouble ; tympany, 

 impaction, paralysis, and inflammation of one or more of the com- 

 partments are common. In spite of the size of the oesophagus, 

 impaction is frequent, in marked contrast to the horse, in which it is 

 uncommon, while calculi, a special feature in the intestine of the 

 horse, are found in the stomach of the ox, though brought about by 

 very different causes. Strangulation of the bowels in the ox is not 

 unknown, but limited to a special variety due to anatomical condi- 

 tions. Parasitic trouble in all animals is a prominent pathological 

 feature, the digestive canal from the mouth to the anus being liable 

 to infection with numerous varieties of parasites, and it also forms 

 the main channel of parasitic entry for other parts of the body. 



