Definition. Causes: overloading, lessened secretion, mastication or insalivation, frosted food, fermenting food, appetizing food, cooked food, debility, disease, starvation, overwork, fatigue, violent exertion after a meal, anæmia, parasitism, injury to vagi or their centres, iced water, wading or swimming in iced water, food with excess of proteids, drink after grain, alkaline waters. Symptoms: in slight cases, in severe, violent colic, weariness, pinched countenance, acid mouth, bloating of abdomen, anorexia, dysphagia, no rumbling of bowels, no fæces, tries to eructate, dullness, stupor, coma, vomiting. Rupture of stomach. Recovery. Lesions: overdistended stomach, ruptured peritoneal hemorrhage, ruptured diaphragm, small bloodless liver and spleen. Diagnosis. Treatment: Aromatics, stimulants, antiferments, laxatives, stimulants of peristalsis, exercise, friction, electricity, chloral hydrate, puncture of stomach and colon, probang, stomach pump, dieting, tonics.
Definition. Suspension of the normal functions—motor and secretory—of the stomach and the supervention of fermentation in its contents.
Causes. The small size of the stomach in the soliped (26 quarts) and the rapidity with which the alimentary matters normally traverse it, render this organ much less subject to disorder than the complex stomachs of ruminants. In his native state the horse eats at frequent intervals and digestion is constantly going on, so that the viscus is never distended to paresis, nor the secretions, nor vermicular movements retarded by excess of ingesta. But the limited capacity of the viscus becomes in its turn a cause of indigestion whenever the animal is tempted by hunger to hurriedly swallow too great a quantity of food; when the decreased secretions fail to act with sufficient promptness on the contents and leave them to undergo fermentation; when from imperfect mastication and insalivation the food is left in large masses comparatively impermeable to the gastric juice, and accumulates in firmly packed masses; when frosted food (roots, potatoes, apples, turnip tops, etc.), taken in quantity temporarily chills and paralyzes the stomach, and starts a speedy and gaseous fermentation; when the food swallowed is already in process of fermentation (musty or covered by cryptogams) and full of toxic fermentation products which tend to paralyze the stomach. Old animals are especially liable because not only are the teeth and salivary glands ineffective, but the functions of the stomach are habitually below par.
The paralysis of the stomach by overloading is seen especially in animals that have been fasting for too great a length of time, and are then furnished with a food, rich, appetizing and abundant. Few horses are proof against the temptation to overeating when they get to the cornbin, the ripening grain or maize, or the field of rich red clover. Some are natural gluttons and on gaining access to grain or green food, will suddenly overload the stomach beyond its power of active contraction on its contents, and without sufficient mastication or insalivation. The food is literally bolted whole, with no admixture of saliva, and no facility for admixture of gastric juice, even if the overloading had left the stomach capable of secreting the latter. Cooked food is especially dangerous by reason of its bulk, the facility with which it is swallowed, and the rapid and excessive dilatation of the stomach caused by it, rather than from lack of trituration and saliva. If fed judiciously, cooked food is more fattening for both horse and ox, any lack of ptyaline being counterbalanced by the presence of amylopsin in the intestines.
Such paresis and indigestion, however, are more common as the result of a general debility or a special gastric atony caused by disease, starvation, overwork or fatigue. In all acute febrile and inflammatory diseases the gastric functions are weak or suspended, and if the animal is tempted to eat, the ingesta is unaffected by the digestive fluids and forms a suitable fluid for injurious fermentations. In convalescence especially, when the starved system once more craves support, tempting food is liable to be taken to excess, unless the attendant is especially judicious and careful in grading the feed as the stomach can dispose of it. The horse that has been starved must be fed little and often, of easily digested material until the gastric functions are restored. Long continued severe work, exhausts the motor and secretory power of the stomach, as it debilitates the system at large, and the animal may be at first unable to digest a feed of grain even if he will take it. In such a case as in that of the very hungry glutton a drink of gruel or a handful of hay which he must masticate will often obviate the danger.
Violent exertion immediately after a meal arrests digestion, and tends to a fatal indigestion. An animal fed grain and immediately put to severe work, or subjected to confinement for a painful operation, may die in two hours from tympanitic indigestion.
This weakness of the digestion may come from profuse bleeding, from the anæmia caused by parasites (sclerostomata), or from injuries to the pneumogastric nerves or their centres. It can be produced experimentally by cutting both vagi; the gastric contents then remain packed and solid, without peptic juices and without digestion.
Iced water, like frozen food, may temporarily arrest the gastric functions and entail fermentation. It acts most dangerously on the overheated and exhausted horse, and though the indigestion may not prove fatal, it may induce a sympathetic skin eruption or laminitis. The mere exposure to external cold is less to be dreaded as there is a compensating stimulus which drives the blood to internal organs, the stomach included. Standing in cold water or wading or swimming a cold river, is commonly less injurious than a full drink of iced water, when heated and fatigued.
Certain kinds of food are far more dangerous than others, and especially such as should be digested in the stomach. Thus the different grains—barley, rye, buckwheat, wheat, oats, Indian corn, and even bran, have been especially objected to. The amount of proteids in oats, for example, is 11.9 per cent., while those of hay are but 7 per cent. The same bulk of oats, therefore, demands nearly double the work of the stomach to reduce its nitrogenous constituents to peptones than does hay. But when fully insalivated the difference is even greater, for oats take but the equivalent of their own weight of saliva, whereas hay takes four times its own weight. There is 1 part of proteids in 16.7 parts of insalivated oats, and but 1 in 71.4 of insalivated hay. If the oats are bolted without mastication, which can never be the case with hay, the discrepancy becomes greater still. Grain is best fed often, in moderate amount, and without further loading of the stomach immediately with either solids or fluids. Above all never feed grain to a thirsty horse and then lead him direct to the watering trough. Even should he fail to have the stomach paralyzed by the cold water, and indigestion developed, yet much of the proteids will be washed out into the small intestine to threaten indigestion there.
Selenitic waters may induce indigestion by neutralizing the hydrochloric acid of the stomach and interrupting digestion.