The ox seems more particularly susceptible to the action of the latter. It shows symptoms resembling those of horses suffering from a severe abdominal form of influenza: profound depression, mahogany-coloured conjunctiva, lachrymation, infiltration of the cornea, high temperature (104° to 106° Fahr.—41° to 41·5° C.), strong action of the heart, but small pulse. The cerebral symptoms are especially marked. The animal suffers from vertigo, and when excited, or when attempts are made to administer medicine, it thrusts its head against the wall, as though suffering from a cerebral tumour. It also shows hyperæsthesia, slight colic, and sensitiveness of the abdomen.
In sheep the symptoms consist in alternate extreme depression and extreme excitability.
In both species the termination is always rapid: death occurs in a few days.
The abdominal lesions are identical with those of the acute form. They consist in gastro-enteritis, or, rather, intense congestion of the abomasum and intestine, with extravasation of blood around the acini of the glands and beneath the mucous membrane, etc., and in more or less marked desquamation of epithelium.
The annexed organs sometimes present secondary changes: in the nervous centres the lesions are more marked; the meninges are congested, in some cases inflamed, and cerebro-spinal fluid is present in increased quantity.
Subacute or Chronic form: Symptoms. This form is equally frequent in the ox and sheep; it develops insidiously, and for a time may escape detection.
The symptoms are those of slight gastro-enteritis without tympanites; but this condition is succeeded by serous, fœtid, uncontrollable diarrhœa, which weakens the animal and causes death from excessive wasting and hydræmia.
The sensitiveness of the entire right side of the abdomen, the special diarrhœa, the cardiac disturbance, and the widely distributed œdema, usually suffice to prevent confusion with the ordinary forms of gastro-enteritis. In sheep the diarrhœa is blackish, sometimes blood-stained, and is accompanied by a sub-icteric or icteric tint of the mucous membranes, of the skin, and of all the tissues. The intensity of coloration affords a guide to the rapidity of development of the disease. The urine is also bile-stained, and there appears to be an exchange of functions between the two great depurative organs, the liver and kidney. The urine may become sanguinolent, because it contains either unchanged blood or simply dissolved hæmoglobin.
The lesions are similar to those previously described, but with modifications of intensity. When diarrhœa has been marked and persistent, the digestive mucous membrane is hardened, indurated, and appears as though tanned. This is due to chronic inflammation, probably to the gastro-enteritis with which the condition begins. The liver appears as if cooked; the fat, the majority of the tissues, and especially the conjunctiva, exhibit a light yellow tint, pointing to hepatic disturbance.
The diagnosis is generally easy in all three forms, provided that the food be examined.