The symptoms of this colic differ very little from those of the preceding with which they are often confused. But in regard to its causation the condition is essentially different. =Causation.= Strangulation of the intestine in the ox may be produced in several different ways: by the passage of a loop of intestine through a tear in the epiploon, through the diaphragm, mesentery, broad ligament of the uterus, the serous layer surrounding the spermatic cord, etc., or by strangulation of an intestinal loop by fibrous bands resulting from chronic peritonitis, etc. Of these various causes, the three principal may here be described:— (1.) Tearing of the mesentery. As a result of mechanical violence the epiploon or mesentery becomes fissured, and the peristaltic movements cause a loop of intestine to pass through and become fixed in the fissure. If the opening is narrow, as is usually the case, the base of the intestinal loop, riding on the lower lip of the slit, becomes constricted by the margins of the opening through which it has passed. [Illustration: $1] (2.) In pelvic hernia a loop of intestine passes between the spermatic cord and the walls of the pelvis. The fissure in this case is in the serous fold which supports the large testicular arteries and the vas deferens. The fold is often ruptured during castration, especially during the practice of “bistournage,” in consequence of traction exercised on the cord. (3.) Pseudo-ligaments and fibrous bands due to chronic peritonitis.—In local, subacute or chronic peritonitis false membranes may become organised, forming fibrous cords or folds connecting the parieto-visceral or inter-visceral surfaces. If by accident a loop of intestine insinuates itself beneath one of these fibrous bands, the passage of digestive material is first impeded and then stopped. The intestine becomes engorged, and symptoms of strangulation soon follow. =The symptoms= appear suddenly, and are similar to those of invagination. They consist of very acute colic, which disappears after ten to twelve hours. The peristaltic movements drive the semi-digested food, whether liquid or gaseous, towards the lower (strangulated) end, from which it cannot escape. It therefore distends the herniated loop and sets up intestinal engorgement. This constitutes the first stage of strangulation, and is accompanied by severe disturbance in the local circulation. The mucous membrane of the intestine becomes swollen and infiltrated, so that it alone soon fills the entire neck of the hernia. Necrosis of the loop of intestine is then only a matter of time. =The diagnosis= of colic by strangulation is difficult. The condition cannot often be recognised at an early stage, and may easily and excusably be confused with invagination. Only in rare cases will rectal and abdominal examination enable one to detect a pelvic or mesenteric hernia.