256 THE COMMON COLICS OF THE HORSE 



colon generally occurs, and this, he says, is due to the 

 anatomical distribution of the bowel. In this way : The 

 second portion of the bowel being larger than the third, 

 and containing a greater weight of ingesta, tends to roll 

 (in either direction, H. C. R.) on the third. Thus, if the 

 animal lies on the left side, the second portion, heavily 

 weighted with ingesta, glides between the abdominal wall 

 and the third portion, coming eventually to lie on the left 

 side instead of on the right side of the abdominal cavity. 

 This of necessity causes the attached third portion to 

 move over the second from left to right. If, when this 

 has happened, the animal then gets up sharply, the bowel ■ 

 by the movement is helped to maintain its abnormal 

 position, and twist, incomplete — that is to say, twist of 

 half a turn — has occurred. 



This we may again express diagrammatically, in which 

 case we have the state of affairs depicted in Fig. 23. 



When compared with Fig. 22, it will be noted that the 

 second and third portions of the colon have changed 

 places. Not only have they changed places, but the 

 superior face has become the inferior, as will be noticed 

 from the changed position of the glands h, b. 



At autopsies the fact that the distal half of the colic 

 loop has thus turned upside down may be noticed if, im- 

 mediately on laying back the abdominal flaps, and before 

 disturbing any of the intestines, careful examination is 

 made of the course of the bowel. Smith draws attention 

 to this in the following words : 



' In conducting the post-mortem examination in cases 

 of this kind, after the flaps of the abdominal walls are 

 laid back (the animal lying on his spine with his legs in 

 the air), note carefully the course of the large bowels, 

 using both hand and eye. . . . As an example of this I 

 give the following : If, on opening the abdomen, a wide 



Digitized by Microsoft® 



