382 DISEASES OF OATTLE. 



The disease had been known in Europe for centuries, but it was not 

 until a comparatively recent date that the erroneous conceptions of 

 its spontaneous origin as a result of climatic and meteorological condi- 

 tions, exhausting* journeys, etc., were abandoned. It is now con- 

 ceded that foot-and-mouth disease is propagated by a specific virus 

 and that every outbreak starts from some preexisting 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 reason 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, barn- 

 yards, 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 authorities 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 ani- 

 mal 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 106° F. Following 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 gams and the inner surface of the lips, or on the mar- 

 gin of the dental pad. These little blebs contain a yellowish watery 

 fluid and gradually become more extensive 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 ten- 

 derness manifest about the feet, at the coronet and between the digits 

 of each foot. Eruptions similar to those within the mouth make their 



