264 THE COMMON COLICS OF THE HORSE 



conditions, as, for example, when attempting to deal 

 with an overloaded state of the bowel (overloading 

 probably to the extent of impaction of some portion of 

 it), then the force exerted must be enormous. Failing 

 to dislodge the impaction, what more likely than that 

 the violent contractions thus brought about result in 

 doubling over the bowel. 



Smith is fairly emphatic with regard to this point; 

 and his remarks are so in agreement with my own views 

 that I quote them here. He says : 



' The actual mechanism which brings about twists of 

 the large and small intestines is disordered muscular 

 action, and disordered muscular action is the result of 

 disordered nervous action. ... In the case of the large 

 intestines the muscular action must be capable of causing 

 the bowel to perform a revolution more or less complete, 

 and in this way reversing its position. We cannot 

 attempt to indicate the exact disordered action which 

 occurs ; this question would require to be worked out 

 on the living subject. The colon is most liberally sup- 

 plied with bands (see Figs. 19, 20, 21), and it does not 

 appear to us to be beyond the bounds of reasonable 

 possibility that these play a most important part in the 

 production of displacements. The cause of the dis- 

 ordered nervous action which leads to this, may, from its 

 physiological interest, be briefly dealt with. Apart from 

 obvious errors in feeding, the most common cause of 

 derangement of the muscular action of the digestive canal 

 is work. It is this which accounts for the majority of 

 of colic cases occurring towards the end of the day, the 

 frequency with which the seizure occurs at or shortly after 

 work, especially that of an exhausting nature, and the 

 practical absence of colic among non-working horses.''- 

 ' Smith, 'Manual of Physiology,' p. 237. 



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