In the more acute cases resulting from a sudden access of green food, a change of water, or the ingestion of irritant plants, the affection partakes more or less of the nature of congestion or inflammation of the viscus, and may run a rapidly fatal course. The animal may be seen apart from the herd in the characteristic recumbent position, with eyes red and glassy, eyelids semi-closed, and much drowsiness and stupor, but when raised he may still feed in a sleepy, listless manner. The bowels may be loose or confined, the pulse and breathing accelerated, the right hypochondrium firm and tender, and as in the other forms the crepitating sound of fermentation is slight or absent over the region of the manifolds. Soon nervous disorder appears, the eyes glare wildly, the animal seeks relief in motion, it may be in a straight line, or to one side, and being blind and unconscious of obstacles he may fall into pits, or ditches, dash against trees, fences or buildings, and if they offer sufficient resistance he will continue pushing, breaking teeth or horns, and subject to violent muscular contractions, causing even the grubs to start from the back. The nervous disorder is often further shown in loud and terrified bellowing as if chased by a dog or gored by one of its fellows.
Course. Chronic cases may continue almost indefinitely the victims showing merely poor health, impaired digestion, and steady loss of condition. After death the omasum is sometimes found to contain dried materials, such as the animal has not had access to for from three to five months.
In those which end in an early recovery there occurs a free and abundant diarrhœa, the fæces containing solid flattened masses with black baked or polished surface, the result of the detachment of the impacted layers from between the folds of the third stomach. The tympany of the rumen subsides, crepitation is renewed in the rumen and omasum, there is free rumbling in the bowels, and the appetite gradually improves. The softening and removal of the dessicated contents are slow and it may be weeks before there is a complete restoration to normal conditions.
Diagnosis. The hurried pulse and breathing and the grunting with expiration may be mistaken for pneumonia or pleurisy, but the distinction can be made as in impacted rumen. There is at first no fever, the tenderness is confined to the right side, the percussion dullness of the chest is in the posterior part and distinctly referrible to the loaded abdominal viscera, it is attended by no pulmonary crepitation, indeed crepitation in rumen and omasum is lessened or abolished, there is no pleural effusion, but there are the unquestionable signs of gastric and intestinal disorder.
It may be confounded with overloading of the rumen, but in the latter case the distension occurs rapidly, there is little or no indication of movement of the viscus, appetite and rumination are usually early suspended and the gaseous eructations are not putrid.
Postmortem Appearances. These are essentially connected with the impaction of the omasum. This organ is gorged to twice its normal size or larger, firm, solid and resistant, not easily taking an impression of the finger, and having at times an almost stony hardness. When incised the intervals between the folds are sure to be packed with dessicated food, often so dry in the upper part that it may be rubbed down into a grayish powder, and it has been compared to the cakes of linseed as they come from the press. The surface of such cakes is smooth and dark, and usually covered by a layer of epithelium which has detached itself from the surface of the fold. This is usually quoted as a morbid desquamation, but inasmuch as we frequently see it in perfectly healthy conditions in animals killed in abattoirs, it must be admitted to occur also as a normal physiological exfoliation. The exposed mucosa shows spots and patches of congestion, extravasation, and even at times ulceration, or slight areas of necrosis.
The rumen shows the result of torpor and inactivity. The ingesta is largely packed into solid masses, which have advanced from the simple acid fermentation, to evident putrefaction with offensive emanations. The abomasum is empty or nearly so of ingesta, but contains abundance of mucus and shows patches of congestion as in prolonged abstinence.
The small intestine is also empty and collapsed, with considerable redness and congestion. The larger intestine contains a small quantity of feculent matter, dry, massed in small pellets and with smooth glistening surface. Mucus is abundant and dense.
Treatment. This must follow the same lines as in impaction of the rumen with the understanding that the response is less certain and the result somewhat more tardy in reaching complete convalescence. In mild and chronic cases a liberal allowance of flaxseed tea, several bucketfuls per day, will often succeed.
In using purgatives those are usually the best which lead to drinking abundantly. For the ox a pound each of Epsom and common table salt, with an antiseptic stimulant like aqua ammonia (3 to 4 drachms) or oil of turpentine (2 oz.) will often act favorably. The sodium chloride is antiseptic, and induces ardent thirst and if there is free access to water, tepid or not too cold, purgation is early secured and the impacted cakes in the manifolds are slowly softened, detached and removed. But unless water is given freely the salt will prove irritating and even injurious.