The theory of microbic origin has been advanced; but although it may be accepted in relation to the intestine, where the most varied organisms abound, it is scarcely so applicable to the stomach, in which acidity is always very marked and must exercise a very energetic antiseptic action. In sucking calves, however, this theory appears the most plausible.
It is quite certain that ulceration may result from the unwise use of drugs, like tartar emetic or arsenious acid, especially if these be administered for long periods; but such ulceration always occurs at the same points, viz., at the deepest portion of the rumen, reticulum, or abomasum.
On the other hand, ulceration due to secretory disturbance occurs at different points, and the figure opposite shows that the mucous folds themselves may be injured and perforated.
Lesions. Ulceration of the abomasum varies in severity. The case referred to showed excavated ulcers from the site of which a portion or the whole of the epithelium and glandular layer had been shed; true round ulcers, which had destroyed the entire depth of the mucous membrane and had produced chronic inflammation and sclerosis of the muscular layer; and finally perforations resembling cleanly punched-out holes.
The Symptoms are those of a mild form of ordinary acute gastritis, without marked fever, and without special injection of the conjunctiva. The appetite is diminished and irregular, but more as a consequence of excessive reflex sensibility of the injured organ than from absence of hunger. This excessive reflex sensibility of the abomasum causes relative or absolute gastric intolerance, so that only a small amount of the food ingested passes towards the intestine.
Absolute intolerance on the part of the abomasum may even occur, as in a case described by Moussu in 1895, which produced a very special form of impaction of the rumen, absolutely different from primary impaction.
Intolerance of the abomasum for food already ingested and ruminated may extend to the omasum. Peristalsis of the rumen then ceases, and slight tympanites occurs. The most characteristic condition is the existence of obstinate constipation. If ulceration takes place without producing any important vascular lesion, which, however, is rare, the fæces are hard and coated, but without other peculiarity; if, however (and this appears to be the rule), local hæmorrhage occurs, the extravasated blood is modified by the gastric and intestinal juices, and the fæces appear of a black, tarry colour. This coloration is very significant, and differs from that produced by the bile. It occurs only in gastric hæmorrhage, and at intervals.
Diagnosis. The diagnosis of gastric ulcer is difficult, and can only be arrived at with confidence when the above-mentioned coloration of the fæces can be detected.
Prognosis. From an economic standpoint the prognosis is grave. The patient may recover; the ulcers may heal, but cicatrisation is always prolonged, and as, on the other hand, the glandular apparatus of the abomasum is generally more or less injured, complete recovery is impossible.
