464 IOWA DEPARTMENT OF AGRICULTURE 
mucus from the mouth of a diseased animal upon the inner surface of 
the upper lip of those to be inocculated. From 50 to 75 per cent of the 
inocculated animals take the disease. 
Cause. — As with outher communicable diseases, the source and origin 
of foot-and-mouth disease has given rise to much speculation. The disease 
had been known in Europe for centuries, but it, until a comparatively 
recent date that the erroneous conceptions of its spontaneous origin as 
a result of climatic and meteorological conditions, exhausting journeys, 
etc., were abandoned. It is now conceded that foot-and-mouth disease is 
propagated by a specific virus and that every outbreak starts from some 
pre-existing outbreak. 
The causative agent of this disease has not been isolated, although 
numerous attempts have been made to cultivate and stain it. Experi- 
ments have shown that the virus will pass through standard germ proof 
filters, thus indicating its minute size and the reasons it has not been 
detected by the staining methods. The contagion may be found in the 
serum of the vesicles on the mouth, feet, and udder; in the saliva, milk, 
and various secretions and excretions; also in the blood during the rise 
of temperature. 
A wide distribution of the virus and a rapid infection of a herd is the 
result. Animals may be infected directly, as by licking, and in calves by 
sucking, or indirectly by fomites, such as infected manure, hay, utensils, 
drinking troughs, railway cars, animal markets, barnyards, and pastures. 
Human beings may carry the virus on their clothing and transmit it on 
their hands when milking, since the udder is occasionally the seat of the 
eruption. Milk in a raw state may also transmit the disease to animals 
fed with it. 
The observations made by some veterinarians would lead us to sup- 
pose that the virus is quite readily destroyed. It is claimed that stables 
thoroughly cleaned become safe after drying for a short time. Hence 
litter of all kinds, such as manure or soiled hay and straw, may remain 
infective for a longer time because they do not dry out. Other authori- 
ties maintain that the virus is quite tenacious and may live in stables 
even so long as a year. They also state that animals which have passed 
through the disease may be a source of infection for several months after 
recovery. 
Symptoms. — In three to six days after the exposure of the animal to 
the infection the disease makes its appearance. It is first indicated by 
the animal suffering from a chill, quickly followed by an invasion of 
fever, which may cause the temperature to rise as high as 10d°F. Fol- 
lowing this in one or two days it will be noticed that small vesicles about 
the size of hemp seeds or peas are making their appearance upon the 
mucous membranes of the mouth at the border and upper surface of the 
tongue near the tip, the inside of the cheeks, on the gums and the inner 
surface of the lips, or on the margin of the dental pad. These little 
blebs contain a yellowish watery fluid and gradually become more exten- 
sive as the disease advances. Soon after the eruptions have appeared 
in the mouth of the animal it will be noticed that there is considerable 
swelling, redness, and tenderness manifest about the feet, at the coronet 
