VESICULAR STOMATITIS OF HORSES AND CATTLE. 7 



typically affected at the bureau experiment station failed to contract 

 the disease when inoculated with the virus three months later, 

 although the control animals became infected promptly. It may be 

 stated that in these cases immunity had persisted for at least three 

 months. Further tests regarding its duration could not be made, 

 because the required infectious material was not obtainable owing to 

 the disease having disappeared. Injections of blood serum from 

 immune animals so far as tested induced no resistance to the disease. 

 Whether the milk of affected cattle is or is not infectious for 

 people has not been recorded, but such milk has been fed experi- 

 mentally to hogs without producing any ill effects. 



DIFFERENTIAL DIAGNOSIS. 



While the disease has not the great economic importance of foot- 

 and-mouth disease, it nevertheless is contagious and causes con- 

 siderable alarm owing to its close resemblance to the dreaded Euro- 

 pean disease. Furthermore, as most writers state, this infection in 

 cattle may be readily confounded with foot-and-mouth disease, and 

 experience has shown that a prompt and exact differentiation is ac- 

 companied with numerous difficulties. The real difficulties surround- 

 ing the diagnosis are best appreciated by those who have faced them 

 with the consciousness that their pronouncement if mistaken would 

 lead on one hand to unnecessary and serious economic disturbances 

 and on the other hand to the spread of one of the most dreaded 

 and easily communicated among animal plagues. Vesicular stoma- 

 titis therefore will prove a menace whenever and wherever it may 

 reappear. For these reasons it is strongly urged that local quaran- 

 tines to prevent its spread be imposed by State live-stock officials in 

 whose territory the disease may be found. All owners and handlers 

 of horses, mules, and cattle, particularly liverymen, managers of 

 stockyards, and stockmen, should be directed to separate sick from 

 well animals, clean and disinfect contaminated premises, and have 

 all infected animals appropriately treated. 



The opinion that the malady is not foot-and-mouth disease is 

 based on the fact that persistent observation of sick animals has 

 failed to reveal certain typical symptoms which would be expected 

 in an outbreak of foot-and-mouth disease. The drooling, vesicles, 

 and erosions are similar in appearance to those produced by foot- 

 and-mouth disease, but in none of the animals examined in the field 

 has there been found any soreness of the feet, which is a common 

 symptom of foot-and-mouth disease. Moreover, many horses have 

 this particular ailment, but horses have not been observed to contract 

 foot-and-mouth disease in any of the previous foot-and-mouth out- 

 breaks in the United States. Hundreds of hogs exposed to the disease 



