At a still more advanced stage, the pulse is small, the temperature lowered, the animal very weak and unsteady and inclined to lie, great emaciation, sunken glazed eye, drooping head, ears and eyelids, and a general fœtor from the skin as well as the dejections, which attracts crowds of flies. By this time there may be passed only bloody mucus mixed with eschars, and having a most repulsive odor.
It is a noticeable fact that the fæces are alkaline, and in man the saliva is acid and destitute of its glycogenic properties, the stomach secretions are alkaline and no longer peptogenic, and the secretion of bile is arrested until improvement sets in.
Course. Duration. Some mild cases recover in two or three days, and in violent cases death may occur at this early date. More commonly the disease continues for two or three weeks before ending in death or recovery. Some merge into the chronic form and may last for months and die in a condition of marasmus. These last cases become mere walking skeletons, with pallid mucosæ, sunken eyes, scurfy hide-bound skins covered with vermin, and the frequently everted rectum is congested and covered with ulcers and eschars. Mortality is from 50 to 80 per cent.
Complications. Most complications are in the direct line of septic infection. Among the most common are hepatic abscess, gangrenous pneumonia, and extensive gangrene of the intestinal walls. In man arthritis, paralysis, parotitis and other secondary affections are seen. In the animal as well we may expect necrotic centres in any organ, from the supervention of a general septicæmia.
Lesions. The carcasses putrefy with extraordinary rapidity being as a rule pervaded by septic microbes and their toxins. The blood is of a deep red, loosely and imperfectly coagulated, and accumulated in the veins and subcutaneous connective tissue.
The large intestines are the special seat of the disease, the walls being found hyperæmic, with concentration especially on the mucous surface which is red, congested, infiltrated, tumefied so that it is easily detached under pressure by the finger, or broken down into a putrid pulp. At other points the epithelium or the whole mucosa has been detached leaving ulcers, varying from mere erosions to the deep and even perforating sores, through which the putrid contents escape into the abdominal cavity. At other points the surface is covered by necrotic masses surrounded by a swollen margin of living mucosa. Elsewhere the eschars have been detached and the granulating base and margin have contracted into more or less perfect cicatrices. The contents of the affected bowel may be largely mucopurulent, or it may be mixed with blood, with eschars and putrilage from the sores and at times with small packed masses of food, but in all cases it is very putrid and repulsive. It always contains the elements of blood and exudation, together with many microbes, the predominance of individual species suggesting the main factors in the pathogenesis. Peyers’ patches and the solitary glands are often the seat of infiltration and ulceration. Virchow points out that in man the lesions are largely concentrated in the flexures of the colon in which the ingesta is longer delayed, and the very convoluted arrangement of the viscus in cattle may be one reason of their special predisposition to the disease.
The small intestines are exceptionally implicated, and the abomasum red, congested, ecchymosed and even ulcerated. The mouth and pharynx are often congested, with erosions and ulcerations on the gums and tongue.
The mesenteric glands are red and swollen or pigmented of a dark gray color, and these or the adjacent connective tissue may be the seat of abscess. The liver is enlarged congested, of a yellowish red color, with granular degeneration and softening. Hepatic abscess is rare in cattle. The spleen is engorged with black blood and distinctly enlarged.
Diagnosis. Dysentery is distinguished from rinderpest by the slower advance of the hyperthermia, by the absence of buccal concretions of epithelium, and of vaginal congestion, and above all by the absence of the virulent contagion by which the rinderpest spreads widely and rapidly, irrespective of special unwholesome environment. The lesions of dysentery are concentrated on the large intestines, while in rinderpest they are extended over the whole alimentary canal, and do not spare other mucosæ.
From toxic gastro-enteritis it is distinguished by the absence of any history or lesions showing the ingestion of a poison and by the concentration of the lesions on the large intestines whereas in poisoning with irritants, the stomach and small intestines are the most liable to suffer.