PROLAPSE OP THE RECTUM AND ANUS. 601 



as low as possible to favour drainage. If possible, division of the 

 sphincter ani must be avoided. In females the vagina forms a con- 

 venient and safe route for arriving at abscesses lying below the rectum. 

 Wilke punctured the abscess wall through the vagina with the finger, 

 and emptied an abscess the size of an ostrich egg, which lay about 

 6 inches from the anus. 



In purulent cellulitis affecting the upper wall of the rectum, 

 drainage into the bowel should only be chosen when the abscess 

 cannot be punctured from without. In the above described case, 

 Moller opened the abscess with a bent trocar (Flourant's), and gave 

 exit to about 2 litres of thick offensive pus, containing fragments 

 of necrotic tissue. As the abscess had refilled next day, the opening 

 was lengthened with a button-pointed tenotome, introduced into 

 the rectum with its cutting surface covered by the hand. Complete 

 recovery took place in three weeks. 



After incising the abscess, the cavity must be carefully washed 

 out with a strong stream of disinfecting material, so as to remove 

 necrotic portions of tissue, and precautions taken for securing 

 drainage of pus. Relapses, however, are common ; in a case described 

 by Verlinde pus formation extended downwards as far as the Achilles 

 tendon ; nevertheless, the animal eventually recovered. 



V.— PROLAPSE OF THE RECTUM AND ANUS (PROLAPSUS 

 RECTI ET ANI). 



Permanent protrusion of the mucous membrane of the rectum 

 through the anus is described as prolapsus ani. As the membrane 

 appears after each act of defaecation, prolapsus ani really consists 

 only in the abnormal persistence of a physiological condition. This 

 protrusion of the mucous membrane is most distinctly seen in horses, 

 and in them prolapsus ani is rather frequent, but it also occurs in 

 dogs and other domestic animals. 



When not merely the mucous membrane but the entire intestinal 

 wall passes the anus, the condition is termed prolapsus recti. The 

 posterior end of the bowel can only pass the anus after rupture of 

 the periproctal connective tissue, but those portions of bowel 

 normally clothed with peritoneum sometimes pass through the pelvic 

 portion and anus, after becoming invaginated in the last part of the 

 rectum, constituting a third condition — prolapse with invagination. 

 We therefore distinguish— (a) Prolapsus ani. (b) Prolapsus recti, 

 (c) Prolapsus recti cum invaginatione. Prolapse of the anus and of 

 the rectum generally results from severe diarrhoea, particularly if 



