grains and other material from an infected farm may spread the disease.

_The period of incubation is short_. Symptoms of disease may be manifested
in from one to six days following exposure.

[Illustration: FIG. 106.--A cow affected with foot-and-mouth disease. Note
the accumulation of saliva about the lips. (From report of the Bureau of
Animal Industry.)]

_The first symptoms_ are fever, dulness, trembling and loss of appetite.
This is followed by vesicles or blisters forming on the mucous membrane of
the mouth, lips, between and above the claws and the region of the udder.
The inflammation of the mouth and feet may be very painful. Long strings of
saliva may dribble from the mouth and collect about the lips (Fig. 106). A
smacking or "clucking" sound is produced when the animal moves its jaws and
lips. The severe pain resulting from the inflammation of the mouth and
feet, and the difficulty in moving about and eating and drinking, cause the
animal to lose flesh and become emaciated. Milk cows may go dry.

_The death-rate is not heavy_. Some writers place it as low as two or three
per cent. Because of the erosions and sloughing of the tissues of the
mouth, feet and udder it becomes necessary to kill many of the animals.
Young animals frequently die of inflammation of the digestive tract. The
immunity conferred by an attack of the disease is not permanent.

[Illustration: FIG. 107.--Slaughtering a herd of cattle affected with
foot-and-mouth disease. (Photographed by S. J. Craig, County Agricultural
Agent, Crown Point, Indiana.)]

The most economical measures of _prevention and control_ are to buy and