322 HERNIA. 



Mechanical influences, such as bites, blows, contusions, etc., 

 may cause an inflammation of the hernia with a thickening oi the 

 pouch, and an adhesion between'it and the contents of the hernia. 

 If tlie injury is severe enough, we may have suppuration in the 

 pouch. In such cases we may have a subsequent mechanical con- 

 traction and reduction of the hernia, especially when the pouches 

 are small, or in some cases the hernia has only been large enough 

 to admit a fold of the omentum. 



Irreducible Hernia. 1. This may be due to an adhesion of 

 the intestinal contents with the hernial pouch. 



2. The union of the intestinal contents with each other (for in- 

 stance, adhesion of the intestines). 



3. From thickening of the omentum, which lies in the hernial 

 pouch. 



4. From strangulation of" the hernia. This, is especially impor- 

 tant, as it may occur in all cases of abdominal hernia and at any 

 time. 



Concerning the causes of strangulation there are three important 

 groups : 



1. Strangulation by extreme distention of an intestinal tube by 

 fecal matter. 



2. A distention of the opening of the hernia, which subse- 

 quently closes on the intestine and strangulates it. 



3. By the intestines becoming twisted in the sac. Invagination 

 is very frequently seen in young animals. 



In many cases we distinguish three stages of hernia, according 

 to the anatomical alterations produced as a consequence of strangu- 

 lation in the prolapsed parts. First, we have a venous hyperemia, 

 then inflammation, and lastly suppuration. In the first stage the 

 veins and capillaries are gorged with blood, and serum is exuded 

 In different directions. In the second stage we observe inflamma- 

 tion of a septic character, which extends from the mucous mem- 

 brane to the serous membrane, as a consequence of the noxious or 

 poisonous contents of the intestines. In the third stage the pro- 

 lapsed parts become necrosed, due to the stricture of blood-circu- 

 lalion. The intestinal portion becomes black, easily torn, dull in 

 color, and covered with gray or greenish spots on its surface, the 

 hernial fluid becomes purulent, and the inflammatory processes in 

 the intestine above the strangulation cause septic peritonitis. 



