Mechanical irritants may cause the lesion and infection atrium in any of the domestic animals, pins, needles, nails, pieces of wire and other sharp pointed bodies being swallowed by horse and ox, and small stones, pieces of bone, and all sorts of irritant objects picked up by the puppy or rabid dog.
Cooked food swallowed hurriedly at too high a temperature is especially liable to start necrotic changes in the single stomach of horse, pig or dog, the ruminant being in a measure protected by the food passing first into the rumen.
The wounds caused by gastric parasites may become the starting points of molecular degeneration and ulceration. In the horse the spiroptera megastoma, s. microstoma, and the larvæ of the various œstri; in cattle and sheep the strongylus contortus, s. convulutus, s. filicollis and s. vicarius; in swine the spiroptera strongylina, Simondsia paradoxa, and gnathostoma hispida; in dogs spiroptera sanguinolenta, and in cats the ollulanus tricuspis act in this way.
Gastric catarrh debilitates the affected mucosa and lays it open to necrotic microbian infection especially in the pyloric sac and on the summit of the folds.
Interruption of the local circulation in the deeper parts of the mucosa as in inflammation and capillary thrombosis, arterial embolism, venous thrombosis, may lead to local sloughing and ulcerous infection. This may be seen in the petechial fever of the horse, malignant catarrh, rinderpest, and anthrax in cattle and sheep, and in canine distemper in dogs. Vogel found ulcers resulting from a gastric aneurism in the dog.
Tumors and infective growths in the walls of the stomach may prove an occasion of ulceration. Thus sarcoma, epithelioma, actinomycosis and tubercle may be the primary morbid lesion in different cases.
Gastric ulcers have also been attributed to morbid nervous influences as in dogs they have been found associated with lesions of the dorsal myelon, and the corpora quadrigemini, and faradisation of the vagus has apparently led to their production.
General constitutional debility has been alleged as a factor, and experimentally in dogs, the hypodermic or intravenous injection of various microbes or their toxins (diphtheritic toxin, Enriquez and Hallion, staphylococci, Panum, Lebert, Letulle, and a bacillus of dysentery in man, Chantemesse and Widal), have produced gastric ulcers.
Symptoms. In horses and cattle these are very obscure, being mainly in the nature of chronic gastritis. In both there are recurrent attacks of slight colicy pains, with tympany in cattle, and gradual emaciation. Vomiting has been exceptionally seen in both class of animal and if the rejected matters are very acid and above all if mixed with blood it is more suggestive of ulcer. In the horse the attacks of colic are mostly in connection with eating. or (in case the ulcer is duodenal) an hour or two after a meal. In this animal it is possible to withdraw liquids from the viscus by the stomach pump, and any hyperacidity or blood may be almost diagnostic. Tenderness to pressure on the epigastrium or hypochondrium is often present, yet the colics of ulceration are often relieved by pressure and friction. Blood is sometimes present as such in the excrements, but more commonly these are simply blackened by the exuded blood as acted on by the gastric acid and intestinal liquids. The bowels may be alternately constipated and relaxed. A gradually increasing feebleness is a characteristic feature and in cattle paraplegia may precede death.
In the carnivora the symptoms are less obscure. The animal is dull, prostrate, weak, lies on its belly, but rarely long in one place, and when up has arched back, stiff movements, and tucked up abdomen. The epigastrium is painful to touch, which tends to arouse vomiting of food or bloody mucus. As in the horse the rejected matters are very acid. Constipation may alternate with diarrhœa, the fæces being blackened (melæna) or even streaked with blood. The occurrence of suffering after meals, the constancy and persistency of the symptoms and the steadily advancing emaciation and weakness are very characteristic. If the tenderness is referable to a given point, it is even more distinctive.