430 Volvulus and Torsion of the Intestine. 



Predisposition: The great length of the mesentery of the 

 small intestine in the horse, the fact that most of the colon lies 

 free in the abdominal cavity of this species of animals, the fur- 

 ther factor that horses are used for work of various kinds ex- 

 plain the frequency of volvulus and torsion in equines compared 

 with its rarity in other animals. Relaxation of the abdominal 

 walls and more voluminous feed are the reasons why torsion of 

 the large intestine is more common in heavy horses than in 

 lighter breeds under similar conditions. 



Pathogenesis. The facts as to pathogenesis are on the 

 whole similar to those which prevail in internal strangulation 

 (see page 415). The main difference between internal strangu- 

 lation on the one hand and volvulus and torsion on the other, 

 lies in the fact that the intestine is not strangulated by another 

 firm tissue in the latter condition, but by other loops of 

 intestine. 



Anatomical Changes. In torsion of divisions of the colon, 



one finds the divisions distal from the twisted place distended, 

 dark purplish to blackish red, sometimes spotted with hemor- 

 rhages ; the mesentery of the two superimposed divisions infil- 

 trated with blood, often gelatinous, the veins in the intestinal 

 wall strongly filled. The latter appears more or less thickened, 

 it is easily torn and is infiltrated with a reddish, serous fluid; 

 the mucosa is blackish red, thrown into folds, pendulous, here 

 and there necrotic. The bowel contains an abundance of hemor- 

 rhagic fluid or pasty feces. The congestion is either sharply 

 defined towards the place of constriction or an anemic strip maj^ 

 completely encircle the whole intestine or may be distinct only 

 on two opposite places of the periphery. Exceptionally the con- 

 gestion may not be very well marked, both on the serosa and the 

 mucosa. 



The direction of the torsion may be from right to left, or 

 vice versa, and it may be determined by the relation of the two 

 left divisions of the colon or by the direction of the longitudinal 

 bands. Twists to the right appear to be somewhat more numer- 

 ous than twists to the left, although in twenty-six cases of tor- 

 sion Wall saw fifteen to the left and only eleven to the right. 



The degree of torsion is very variable. Usually one finds 

 one-half or one entire twist, but several twists are by no means 

 very rare. 



The site of torsion (place of twisting, torsion-stricture) is 

 usually found in the transverse colon (diaphragmatic flexure), 

 but, in consequence of falling down of the proximal parts in the 

 region of the right divisions, it ma^^ be displaced towards the 

 cecum or to the beginning of the small colon (place of torsion at 

 the root of the colon) and then the cecum mav occasionally 

 also be twisted. (Wall, Berlin report 1900-1901.)" Longitudinal 

 torsion confined to the pelvic flexure has only been described in 



