602 



SYMPTOMS OF PROLAPSE OF THE ANUS. 



accompanied by tenesmus. The disease is favoured by weakness, 

 with relaxation or paralysis of the sphincter ani. It is commonest 

 in young animals, but in swine it also occurs at a later period. 



As a rule, the immediate cause is increased abdominal pressure, 

 as in slinging, though inflammatory swelling of the mucous membrane 

 of the rectum may cause prolapse, and both these have been seen 

 after use of irritant or excessively hot clysters. Prolapse also appears 

 during colic or obstruction of the bowel, sometimes in difficult par- 

 turition ; in cows in connection with prolapse of the vagina, and 

 in horses from halter casting, or from violent struggling during opera- 

 tions. In two cases noticed by Mauri, which occurred during castra- 

 tion, the prolapsed rectum was ruptured, and coils of small intestine 

 protruded through the opening. 



Fig. 421. — Prolapsus recti with invagination in the bitch (semi-diagrammatic) 



Symptoms. In prolapsus ani, a red, slightly painful, hemi- 

 spherical swelling of the mucous membrane appears at the anus, 

 and shows at its centre a shallow depression ; sometimes only a 

 few folds appear at one side. In simultaneous prolapse of portions 

 of the rectum (prolapsus recti) the swelling is larger and harder, 

 but even then does not attain the size usual in prolapse complicated 

 with invagination, where a portion of bowel several yards in length 

 may hang from the anus. In dogs, Moller has repeatedly seen 

 prolapses 12 to 20 inches in length. On account of the tension on 

 the mesentery, the prolapsed portion sometimes becomes twisted 

 upwards in horses (Fig. 422). 



When the prolapse attains such dimensions no doubt can exist 

 in diagnosis, but it is otherwise when only small portions of bowel 



