

VESICULAR STOMATITIS OF HOUSES AND CATTLE 5 



limits. In fact, certain writers have claimed that it is not con- 

 tagious, because they fail to reproduce the disease after experiment- 

 ing with only one healthy animal. Our experience with this disease 

 shows that frequently one or even more of the inoculated animals in 

 an experiment will fail to develop the infection, as in several in- 

 stances we have produced the disease in only two out of three, or 

 two out of four, or, again, three out of nine of the experimental 

 animals; so that it is necessary to use more than one animal if ac- 

 curate information is to be obtained. This point is strongly brought 

 out by the opposite conclusions reached by the two French investi- 

 gators, Jacoulet and Vigel, who found the disease in American horses 

 shipped to France. The former believes the disease is benign, non- 

 transmissible, and of alimentary origin, while the latter readily 

 transmitted the disease to other horses and convinced himself of its 

 contagiousness. 



Experiments have proved that the disease is most virulent at the 

 time the blisters rupture or shortly thereafter, but when the lesions 

 are five or six days old the virus of the disease has practically dis- 

 appeared. This may account for the greatly differing results in- 

 vestigators have had in their attempts to transfer the disease arti- 

 ficially. These facts show the necessity of using several experiment 

 animals for inoculation, and also of injecting the infectious material 

 as soon as possible after the blisters have formed. 



The virus is evidently of short life, and is transmitted only by 

 close contact. Probably the infected environment remains dangerous 

 longer than the affected animals. At the Bureau of Animal Industry 

 Experiment Station one field was set aside for animals which had 

 recovered from attacks of vesicular stomatitis. Horses and cattle 

 were placed in this field 3 weeks after they first showed symptoms of 

 the disease. Healthy susceptible^ cattle were kept in this field as 

 a check on the possible spread of the disease, but in no instance did 

 they become infected. Likewise, susceptible animals turned into a 

 stable which 3 weeks previously in one instance, and 16 days pre- 

 viously in another instance, had harbored active cases of vesicular 

 stomatitis, remained well. Several instances have been reported in 

 which a line fence or a board fence in a double corral has been suffi- 

 cient to prevent transmission of the disease from the infected animals 

 on one side to the healthy animals on the other. 



Investigations indicate that the disease is very seldom communi- 

 cated by owners or caretakers of affected animals visiting other 

 farms. As a rule the disease appears to spread by direct contact with 

 recently affected animals, or by recently infected feed troughs, water 

 troughs, bridles, or pails. Inoculation experiments on such labora- 

 tory animals as rabbits, guinea pigs, rats, and mice have resulted 

 negatively. The disease manifests itself in susceptible animals 

 more rapidly after the application of infectious material to scarified 

 areas in the mouth than through intravenous injection, although 

 positive results have been obtained also by the latter method. 



Contrary to experiences in the field, we were able in several test 

 inoculations to transmit infection to the feet of cattle in a small pro- 

 portion of cases, and likewise this virulent material also produced 

 lesions in from five to nine days in the feet of one hog, in the mouth 

 of another, and on the snout of the third. While these cases were 

 the exception and not the rule, they should be recorded for their 



