FOOT AND MOUTH DISEASE 433 
It has become firmly established in Europe. From there it has been 
carried to almost every cattle raising country. 
Etiology. The value of the specific cause has not been clearly 
demonstrated. It has been shown, however, that it is a specific infec- 
tion and that every outbreak starts from some previous case or cases. 
The virus is contained in the eruptions and escapes from the broken 
vesicles. Loeffler and Frosch found that it would pass through the 
coarser Berkefeld filters but that it was held back by the finer Kitasato 
bougie. 
Animals may be infected directly by coming in contact with the 
disease, or indirectly by being exposed to the virus in stables, cars or 
other places recently occupied by infected animals. It is stated that 
the virus is destroyed in a short time by drying, but some writers 
maintain that it will persist for several months. Penberthy states 
that under ordinary circumstances the virus does not retain its infec- 
tiousness long. Animals that have passed through the disease may 
carry the virus for several months. Loeffler and Hess found animals 
to transmit the virus occasionally seven months after recovery. The 
infected matter may be carried on the clothing or hands of human 
beings and thus be transmitted to animals or man. Milk is often the 
earrier of the virus. In the recent outbreak many animals were 
infected by being fed unpasteurized milk from creameries. 
The period of incubation is usually short, from 24 to 72 hours in 
inoculated cases and from two to seven days after natural exposure. 
In the recent outbreak there were cases that developed after a much 
longer period. 
Symptoms. The symptoms of foot-and-mouth disease vary greatly 
in different epizodtics, sometimes they are quite mild and at others 
very severe. The first evidence of the disease is a rise of temperature 
which in cattle rarely exceeds 104° F. The mucous membrane of the 
mouth becomes reddened, the appetite is diminished, the muzzle dry; 
coat staring and rumination ceases. The mouth is usually kept 
closed and the quantity of saliva is increased. A peculiar smacking 
sound is not infrequently made by the animal. These symptoms are 
chiefly due to the pain accompanying the lesions in the mouth. After 
two or three days the eruption appears. This consists of small 
yellowish-white vesicles or blisters, varying in size from a hemp seed 
to a centimeter or more in diameter on the gums and inner surface of 
the lips, the inside of the cheeks, the border and the under surface of 
