Animals carrying the virus are introduced into susceptible herds. Contaminated facilities are used to hold susceptible animals. Contaminated vehicles are used to move susceptible animals. Raw or improperly cooked garbage containing infected meat or animal products is fed to susceptible animals. Susceptible animals are exposed to materials such as hay, feedstuffs, hides or biologics contaminated with the virus.
Susceptible animals drink common source contaminated water.
Often blisters may not be observed because they easily rupture, leading to erosions. Ruptured vesicles discharge either clear or cloudy fluid and leave raw, eroded areas surrounded by ragged fragments of loose tissue. Sticky, foamy, stringy saliva is produced. Consumption of feed is reduced because of painful tongue and mouth lesions. Lameness with reluctance to move is often observed.