Now and again, in the course of violent paroxysms of straining, the rectum, or posterior bowel, is forced through the anal opening, with the inner or mucous membrane turned outward. The extent to which this extrusion may take place varies in different cases from a few inches to two or three feet. Old animals, brood mares in particular, are more liable to inversion of the rectum than younger ones, and especially those affected with habitual constipation, which appears to act as a predisposing cause. Straining is the inducing factor in the mishap, which sometimes occurs during the pains of parturition or in the course of an attack of colic, or in violent efforts to empty the bladder when the urinary passage is obstructed. It may also arise in the act of straining from severe irritation of the bowels.
Inversion of the rectum is indicated by the protrusion of a round fleshy-looking mass from the anus (fig. 110). At first it presents a pink or pinkish-red hue, but after having been exposed for some time its colour is greatly heightened by engorgement of the vessels with blood, consequent upon interruption to the circulation. In prolonged exposure the mucous membrane becomes considerably swollen, and black, and softened by infiltration with serum. In this condition the part becomes painful and irritable, and unless carefully guarded the animal will endeavour to rub it against the wall or stall-posts. Should it succeed, the'softened and inflamed gut may be irretrievably damaged.
When the bowel has been exposed for some time, and is found to be black, soft, and swollen, an attempt to return it should not be made until the circulation has been restored and the swelling reduced. For this purpose it may require to be scarified with the point of a lancet, i.e. punctured here and there lightly with the instrument to give exit to the serum which infiltrates the tissues, and at the same time relieve the vessels of their burden of blood. This will be rendered more effectual if, after the operation, the protruded gut is wrapped in flannel and well fomented with warm water.
It should be strictly observed that the lancet employed for the purpose is thoroughly clean, and that the flannel is well soaked with carbolic solution, and afterwards well scalded before being used. Neglect of these precautions may provoke fatal blood-poisoning.
It will very materially assist restoration of the circulation if, as soon as observed, the protruding mass is raised and supported on a level with the anus by means of warm flannel.
Before attempting its return the mucous membrane should be freely anointed with carbolized oil, and the hands of the operator should be similarly treated.
Fig. 110. - Inversion of the Rectum.
If the inversion is considerable the attempt must be commenced at the end nearest the anus, where the bowel should be gently pushed forward by applying the fingers on each side of the gut. When a start has been made at this point and a fair proportion of its length has been replaced, the doubled fist of a small hand may be applied to the other end with gentle forward pressure, which will effect its complete return.
This done, the hand and arm should be allowed to remain in the rectum for a short time, after which a small quantity of warm carbolized oil may be injected into the passage.
A full dose of morphia given subcutaneously will prevent straining. The animal should not be left alone for twelve hours, and only a small quantity of sloppy bran should be allowed during that period. Should the bowel be again inverted, it must be promptly returned and the morphia repeated.