228 MANUAL OF EQUINE MEDICINE. 



consist of mineral substances, as phosphate of lime and 

 magnesia. 



The larger concretions are more frequently found in the 

 pouches of the large intestine, from which they are liable to 

 be displaced by the movements of the animal. 



2. Causes acting on the walls of the gut, as inflammatory 

 thickening, or stricture of any portion of the small or large 

 intestine. These causes are rare in the horse. 



3. Causes acting on the gut from ivithout, resulting in 

 altered position or displacement. As examples may be 

 mentioned strangulation by bands of lymph, or, in rare 

 instances, by mesenteric tumours, the neck of which wraps 

 round the gut, and also twists and displacements of various 

 kinds. 



The colon may be found twisted round on itself, and some- 

 times the small intestine is entangled, owing to twisting or 

 laceration of the mesentery. Not uncommonly a loop of the 

 small, and sometimes of the large, intestine passes through 

 an opening in the peritoneal covering. 



Umbilical and inguinal hernias may also cause obstruc- 

 tion, as also may intussusception, or the passage of one part of 

 the boivel into that immediately beloiv it. This condition is 

 very rarely met with in the horse, and is of more frequent 

 occurrence in the young than in adult animals. 



General Symptoms of Obstruction. — The symptoms of in- 

 testinal obstruction, which mayproceed from so many different 

 causes, are very variable. 



When the obstruction results from impaction of faeces, or 

 from the presence of concretions, the symptoms are usually 

 gradual and of an intermittent character. 



The other forms are generally more sudden in their onset ; 

 but we know of no diagnostic symptoms peculiar to twists, 

 intussusception, or strangulation of the intestines in the 

 horse. 



