174 DISEASES OF THE DIGESTIVE APPARATUS. 



openiûgs of the peritoneal cavity, inguinal ring (even in geldings)^ 

 Winslow's hiatus, old lacerations of the diaphragm, ruptures of the 

 omentum and of the mesentery, openings existing between old adhe- 

 sions, or between the detached ureter and the upper wall of the 

 abdominal cavity, etc. Roll has found 51 cases of internal hernia 

 in 140 horses that had died of colic — a proportion of 36 per cent. 



Etiology. The causes of these anomalies are most obscure. 

 There are some which are related to the thrombo-embolic processes 

 described previously ; others are produced by the unequal weight 

 or the volume of the solid, liquid, or gaseous contents of the vari- 

 ous portions of the intestine ; here the volvulus operates according 

 to the laws of gravity, the heaviest intestinal loops. taking a depend- 

 ing position in the abdominal cavity. The frequent and forcible 

 peristaltic contractions ^vhich accompany certain colics may deter- 

 mine changes in the relations of the intestine. 



Finally, rolling and all unusual and violent movements, which 

 the horses are apt to perform, produce a certain influence in the 

 generation of volvulus, knots, and hernias. Cold drinks have been 

 erroneously given as a cause. 



Symptoms. There is nothing very characteristic. At nrst 

 they are most variable : sometimes the intestinal obstruction is 

 revealed with the abruptness of a strangulated hernia, at other 

 times, on the contrary, its symptoms develop slowly. Vomitings 

 are observed in some instances which persist for several days ; in 

 other cases they are absent. The abnormal positions, such as the 

 dorsal decubitus, the intensity of sufferings, the symptoms of a 

 rupture of the stomach or intestine, and the infrequency or impos- 

 sibility of the act of defecation, are manifestations which have been 

 specially recorded in the article upon Strangulations and Lacera- 

 tions, but these are also seen in most colics of impaction. The 

 duration of the affection varies according to the complete or incom- 

 plete intestinal obstruction ; it may persist as long as a week. In 

 complete occlusion death is generally produced within twenty-four 

 hours. These colics are sometimes intermittent, periodical ; they 

 disappear suddenly, then reappear in the same way at variable in- 

 tervals. These conditions are observed when an intestinal loop is 

 incarcerated at certain moments and free again at others ; the colics 

 of short duration which are called frappeurs de nuit (night-strikers) 

 belong perhaps to this group.^ 



1 Stohrer : Repertor., 1877. 



