The Abdomen 177 



to the greater fermentative changes occurring in their bowels, such 

 changes stimulating inordinate peristaltic movements. It is not un- 

 common to find multiple invaginations existing at one time. Var- 

 nell cited two instances observed by Leach, the subject being two 

 pointer puppies of the same litter which had died about the same 

 time, the intestine of each showing four separate invaginations. 

 The vessels of the most inferior ones only were strangulated sug- 

 gesting that the others might possibly have been of agonal or post- 

 mortem origin. 



The duodenum may become invaginated within the stomach. 

 Peuch recorded an instance, the invagination forming a non-ad- 

 herent reddish cylindrical tumor some two and one-half to three 

 inches in length. 



The small intestine may work its way into the colon and even 

 protrude from the anus. Such cases are apt to be mistaken for 

 simple procidence of the rectum unless carefully differentiated. 

 Dudfield saw a case of ileo-colic invagination. Petit found seven 

 instances of ileo-colic invagination of probable agonal origin at a 

 number of necropsies conducted by him in less than a year. Death 

 in these cases resulted either from pneumonia or icterus. Cases have 

 been recorded of the healthy bowel intruding itself into a dilated 

 portion following the removal of a fecal obstruction. 



When an intussusception is established, the mesentery which 

 contains the blood-vessels is drawn into and included in the tumor. 

 There is necessarily pressure with consequent stasis of the circula- 

 tion in that part and gangrene of the entering and returning layers 

 may follow. Gangrene is less apt to affect the intussusceptum than 

 the intussuscipiens. The mucosa of the latter becomes extremely 

 red or blackish and congested, while the mucosa of the former may 

 be almost normal, though all the coats are usually somewhat 

 blanched. A clot of blood may exist between the two mucosal mem- 

 branes. The mesentery being attached to one side of the bowel it 

 draws on that side so that the tumor has a more or less curved ap- 

 pearance. The length of an intussusception generally varies between 

 five and ten inches. The lesion may be acute or chronic. The acute 

 form is accompanied with severe colic but the chronic condition may 

 exist without causing any apparent inconvenience to the animal. In 

 some of Senn's artificial invaginations no symptoms of obstruction 

 were witnessed, and when the animal was killed weeks or months 



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