Diagnosis. The diagnosis is based on the exceptional sensitiveness of the gastric compartments on palpation, and also on the history, provided reliable information can be obtained.
Prognosis. The prognosis should be reserved, because it is never possible to foretell whether acute lesions may not give place to chronic disease, which, though apparently unimportant, may terminate in grave consequences.
Treatment. Owing to their local action demulcent drinks and teas are indicated. Cooked food is useful, because it makes little demand on the digestive powers; steamed hay and farinaceous substances are given, both on account of their nutritious qualities and of the slight local irritation they cause when swallowed.
Lukewarm drinks and saline laxatives, such as the sulphate of soda, and carbonate of soda or Carlsbad salt in small doses of 1½ to 2 ounces, seem most useful in combatting the reflex atony of the digestive compartments.
Inflammation of the omasum, like that of the rumen and reticulum, occurs as a secondary phenomenon in conditions like rinderpest, Texas fever, foot-and-mouth disease, anthrax, and gangrenous coryza (malignant catarrh); but primary inflammation is much rarer even than that of the rumen and of the reticulum.
This is accounted for by the deep position of the omasum, which is thus sheltered from external violence, early contact with irritant foods and from the effect of chills, etc. It can only become inflamed by the prolonged action of irritant food and drink, which have already produced lesions in the rumen and reticulum; or as a consequence of the prolonged stagnation of dry food in cases where animals have been deprived of water.
Under these conditions inflammation of the omasum develops slowly, and from the clinical point of view is identical with what was formerly known as obstruction of the omasum. Obstruction or impaction is probably much rarer than has been stated, in so far at least as it constitutes a primary condition, for in the great majority of cases it is consecutive to impaction, inflammation of the rumen, or inflammation of the abomasum. Obstruction of the omasum, which was formerly invoked in all doubtful and ill-defined cases of digestive disturbance, seldom occurs as an isolated disease.
It has been suggested that the omasum, being supplied with nerves solely by the sympathetic system, and provided with a relatively weak muscular coat, was more susceptible than the other reservoirs to the reaction of abdominal reflexes, and therefore more subject to inflammation, indigestion and obstruction. We do not hold that view, because, as a result of its general situation and the position of its orifices of communication, this compartment is easily able to expel its contents so long as they are liquid. Its function appears chiefly to be to complete the trituration of food after rumination.
We do not consider that inflammation of the omasum never occurs, for we are well aware of the contrary, and that the inflammation assumes a subacute course and is accompanied by stasis of the semi-digested food between the mucous leaves which partly fill the cavity. We simply wish to emphasise the view that the condition is not a primary and isolated inflammation.
Symptoms. The symptoms are always vague and very difficult clearly to define.