This disease, which is one of the most easily transmitted of contagious and infectious diseases of domestic animals, is characterized by the appearance of vesicles or small bladders on the mucous surfaces and those parts of the skin uncovered by hair, such as in the mouth, on the gums and palate, on the tongue, and the internal surface of the lips and cheeks; on the surface of the udder and teats, and between the claws. The disease passes through four different stages or periods; but for present purposes it will be sufficient to merely mention the most prominent of the successive changes and appearances, as they occur to the ordinary observer. The incubatory stage, or the time between contamination and the development of the disease, is very short (from twenty-four hours to one or two weeks), and the disease is ushered in by the general symptoms of fever, such as shivering, increased temperature, staring coat, dry muzzle, dullness and loss of appetite. The animals seek seclusion, preferably in sheltered places, where they assume a crouched position, or lie down, and there is more or less stiffness and unwillingness to move. The mouth becomes hot and inflamed looking, and covered with slime, the breath fetid; the animal grinds the teeth, smacks with mouth, and has difficulty in swallowing. There is more or less tenderness of feet and lameness, and in cows the udder becomes red and tender, the teats swollen, and they refuse to be milked. Depending upon the intensity of the fever and the extent to which the udder is affected, the milk secretion will be more or less diminished, or entirely suspended; but throughout the disease the quality or constituents of the milk become materially altered; its color changes to a yellow; it has a tendency to rapid decomposition, and possesses virulent properties. Soon yellowish-white blisters, of various sizes, from that of a small pea to a small hickory nut, appear on the mucous surface within the mouth, and which blisters often in the course of development become confluent or coalesce. They generally break within two to three days, and leave bright red, uneven, and ragged sores or ulcers, to the edges of which adheres shreds of detached epithelial tissue. The animal now constantly moves the tongue and smacks the mouth, while more or less copious and viscid saliva continually dribbles from the mouth. The lameness increases in proportion as the feet are affected, and if the fore feet are most affected, the animal walks much like a floundered horse, with the hinder limbs advanced far under the body, and with arched back. The coronet of the claws, especially toward the heels, becomes swollen, hot, and tender, causing the animal to lie down most of the time. The blisters, which appear at the interdigital space of the claws, and especially at the heels, break in the course of a day and discharge a thick, straw-colored fluid; the ulcers, which are of intensely red or