As more direct irritants, may be named irritant plants, weedings and culls from gardens, musty and spoiled fodders of all kinds, newly harvested grain, and putrid drinking water. Also intestinal parasitism, diseases of the heart and lungs, and thrombosis of the mesenteric arteries. _Lesions._ These predominate in the small intestine in catarrhal enteritis as they do in the large intestine in dysentery. The small intestine and cæcum may be distended by gas, and reddened more or less deeply on their outer surface. The mucosa is the seat of congestion, punctiform and ramified redness, thickening, infiltration and softening so that the epithelium breaks down into a pulp under the pressure of the finger. Desquamation may be extensive leaving a raw angry surface. The villi are infiltrated, erect, and ulcerated showing dark bloody points, and ecchymoses, and circumscribed sloughs and eschars are present. The solitary glands are congested, hypertrophied and projecting. The submucosa is infiltrated with a gelatinoid material and the same may be found around the swollen and congested mesenteric glands. Perforations have been met with in some cases, and coexistent inflammatory lesions in the stomachs are common. _Symptoms._ In the _mildest forms_ there is inactivity of the rumen, aggregation of the contents into hard masses, easily felt through the surrounding gases, appetite and rumination are greatly impaired, and there is much rumbling and considerable tenderness of the right side of the abdomen, and more or less costiveness, with hard, glazed mucus-covered fæces. There is some rise of temperature, ardent thirst, injected mucous membranes, dry, hot muzzle, weeping eyes, a small, hard, weak pulse, arched back, tender to pinching, and tucked up abdomen. There may be slight colicy pains, uneasy movements of the hind feet and tail, and sometimes lying down and rising at short intervals. In _more severe cases_ the impaction and tympany of the rumen are more marked, the hyperthermia runs high, appetite and rumination cease, the milk dries up, rigors and tremors appear, the head and ears droop, the eyes are sunken, the mouth is clammy and fœtid, the colicy pains are severe or extreme, the right side of the abdomen is very tender, defecation may be altogether suspended and rumbling in the right side of the abdomen ceases or becomes rare. Straining may continue but seldom is anything but mucus passed. Eructations from the rumen are distinctly fœtid. After the third day the violence of the pains may abate, and sometimes diarrhœa sets in and may be regarded as critical, and portending recovery. If rumbling in the right side is resumed, if the fever subsides, the spirits revive, and some appetite and rumination return they will herald improvement.