For various reasons presently to be indicated, we do not include this disorder under the title of constipation. Here the food, or whatever else may be the offending body, is arrested in its course along the bowel, and caused to block up the passage.
The causes which bring about intestinal obstruction can invariably be referred either to some abnormal state of the bowel itself, or to the nature and condition of its contents. As to the former, it is found to follow upon both physiological and structural changes. The first is exemplified in that state termed debility of the bowels. Here the muscular portion of the organ fails to carry on its movements with normal activity, and allows the food to accumulate and obstruct the canal. Such cases are most frequently met with in colts which have been ill-fed and badly nourished from the time of weaning, and in old horses long and luxuriously fed on hard food. It is sometimes spoken of as paresis of the bowels, and the description is not altogether inappropriate to the affection. The second condition is seen to arise in the form of a thickening of the gut, either as the result of inflammatory action or from the growth in or upon it of one or another of the various forms of tumour, or the passage may be obstructed by the gut being twisted, intussuscepted, or displaced.
Where obstruction results from matter contained in the bowels, it is attributable to the indigestion of coarse food imperfectly masticated, or to some foreign substance taken in with it. An equally common cause is the formation of calculi and concretions, fig. 105, or, as they are commonly termed, "stones". These are especially found in horses engaged in town work and living exclusively on dry food.
The symptoms observed in this disorder are by no means uniform or diagnostic. They may vary from intermittent colicky pains observed in debility of the bowels, to the most severe paroxysms of suffering exhibited in the twists and entanglements into which they are sometimes accidentally brought. In all cases, however, the discharge of fasces sooner or later ceases.
Fig. 105. - Portion of Intestine impacted with Concretion.
A, Concretion; B, divided intestine thrown back; c, mesentery.
In order to find out the cause, it is necessary to consider every detail in the history of the case and let in all the side-lights obtainable from every source.
Fig. 106. - Strangulated Bowel.
There are many causes of obstruction which yield promptly to purgatives and the method of treatment prescribed under the head of constipation. This is more especially the case with those due to functional impairment of the bowels, but since the cause of obstruction cannot always be definitely ascertained, treatment must sometimes be speculative and the result consequently uncertain.
Oily laxatives, as castor and linseed oils, or aloes, are indicated, and in all cases solid food should be withheld until the obstruction is caused to give way. Some benefit will be found from the repeated injection of enemas of tepid water with which a little salt and salad oil has been mixed. Pain must be subdued by the administration of sedatives and antispasmodics. Here tincture of opium, or the extract of belladonna, or the two combined, will be found most suitable to the case. Where acute pain exists hot fomentations to the abdomen should be applied, or, as an alternative, mustard or turpentine liniment.