DEFINITION.—An acute, contagious fever, characterized by the formation of vesicles and ulcers, chiefly about the mouth and hoofs, etc. The eruptions appear on the mucous membrane of the mouth, on the fetlock, and in the cleft of the hoofs, and not unfrequently as a eruption on the udder. The disorder chiefly prevails among cattle and sheep, but under favoring circumstances, also attacks other domestic quadrupeds, and even man. CAUSES.—It appears as an epidemic, and spreads exclusively by contagion. The precise nature of the germ is unknown, but it is chiefly limited to the contents of the vesicles, the secretion of the ulcers, the saliva, the blood and the natural secretions and excretions, of the diseased animal; and these convey the disease. The predisposing causes are exposure to cold, wet, currents of cold air, poor fodder, want of cleanliness and good housing; and anything that tends to lower the constitutional vitality. The activity of the virus is preserved for many months. The poison may be conveyed by the clothes of herdsmen and other persons, by manure, tools, fodder, by grass and ground previously trodden by diseased animals, and milk to sucking calves, indeed by almost anything. It finds its way into the system in various ways, not depending on any wound for admission. The communication to man is by drinking the milk of diseased cows. A second attack is rare. SYMPTOMS.—After a period of incubation, lasting from three to six days, the animal is seized with a shivering fit, and appears dull and stupified. A vesicular eruption soon appears on the mouth, the hoofs, and the teats. Sucking calves have a similar eruption on the fauces and pharynx, with irritation of the whole alimentary canal, attended with inability to suck, and exhausting diarrhea. The eyes are then observed to be dim, watery, congested; the muzzle, ears and horns alternately hot and cold; shivering ensues; rumination is diminished; the milk is less in quantity, yellower and thicker than usual, and much deteriorated in quality; the bag swollen, tender, hot; the back arched; the coat staring and harsh; the pulse somewhat accelerated; the temperature moderately elevated, reaching 102°, or even 104°; the eruption in the month is first seen on the inner surface of the upper lip, the edge of the upper jaw where there are no teeth, on the tip and edges of the tongue, and is indicated by salivation, by pain and loss of power in taking and eating food. The vesicles occur on the mucous membrane, singly or in patches, first as little red spots, then as whitish-yellow, slightly turbid blisters, about the size of a bean, at first transparent, but subsequently filled with a puriform fluid. These vesicles burst in about eighteen hours, discharge their fluid, leaving behind shallow ulcers, which often run together and then form deep and ragged ulcers. The lips, cheeks, tongue, and sometimes the Schneiderian membrane, are affected.