30 THE COMMON COLICS OF THE HORSE 



of the cardiac extremity of the oesophagus ; the obHque 

 manner in which the latter enters the gastric walls ; the 

 peculiar arrangement of the folds of mucous membrane 

 lining its interior ; and the presence of the cardiac 

 sphincter, already described on pp. 9 and 20— these are 

 all factors in bringing about complete occlusion of the 

 oesophageal opening. 



3. The pyloric outlet — comparatively distended — 

 lying close to and below the sealed oesophageal inlet. 

 That being so, it naturally follows that any compression of 

 the gastric walls forces the stomach contents with equal 

 strength towards both the oesophageal and duodenal 

 openings. The contained material finds the readiest 

 road of exit — the pylorus. The offending material, which 

 may have given rise to inclination to vomit, is passed by 

 adverse force of circumstance into the intestine. 



Proceeding with the intestines themselves, we note 

 first of all the formation of the so-called ' duodenal trap,' 

 as illustrated on pages 10 and 11. In cases of distended 

 stomach or intestines this S-shaped piece of intestine is 

 compressed and its contents rendered stationary. This 

 is undoubtedly another great factor in the production of 

 gastric and intestinal obstructions, with their attendant 

 colicky pains. Following this, we observe the differences 

 in the size of the various parts of the colon, together with 

 its several flexures, and note also the length and com- 

 paratively free location of this organ and the caecum. 

 Taken collectively, these circumstances, though quite 

 normal in themselves, must still be held to be favourable 

 to the production of colic. 



Again, I think every practitioner will bear me out 

 when I say that age is frequently a predisposing cause of 

 these complaints. With advancing age there is not the 

 amount of what is commonly called ' tone ' in the system. 



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