VESICULAR STOMATITIS OF HORSES AND CATTLE 7 



ticular ailment, but horses have not been observed to contract foot- 

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

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

 and in association with the sick animals in pastures have shown no 

 signs of the malady, which is regarded as significant, because in 

 the 1914 outbreak of foot-and-mouth disease hogs were as susceptible 

 to that disease as were cattle. Exposed sheep also failed to show 

 vesicular stomatitis, yet these cloven-footed animals are susceptible 

 to foot-and-mouth infection. In a number of cases of vesicular 

 stomatitis the lesions appeared to be continuous or progressive, and 

 not explosive, as in foot-and-mouth disease. In these instances 

 secondary lesions were apparent on a number of consecutive days in 

 the mouths of both horses and cattle, and vesicles were observed on 

 the bases of tongues whose free portions were almost denuded of 

 mucous membrane as a result of the rupture of similar vesicles six 

 or seven days before. 



Complications are extremely rare in vesicular stomatitis, and 

 neither mammitis nor chronic diseases of the hoof have been observed 

 following it. Sucking calves are seldom affected with the disease, 

 and rarely in other than a mild form, while an attack of foot-and- 

 mouth disease in calves is always serious and not infrequently fatal. 

 The vesicles in foot-and-mouth disease as a rule are larger than in 

 vesicular stomatitis, and are more tightly filled with serous fluid. 

 Furthermore, instead of increasing in virulence by passage through 

 a series of calves, as foot-and-mouth disease has always done in our 

 previous experiments, vesicular stomatitis became greatly reduced 

 in pathogenesis and required a constantly increasing period of incu- 

 bation before manifesting lesions of the disease. Although numerous 

 filtrate experiments have been conducted, in no case has the disease 

 been reproduced in this manner, which is also unlike our experiments 

 with foot-and-mouth disease. •• 



The percentage of animals infected in each of the herds of cattle, 

 and the history of exposure without transmission of the disease 

 except by immediate contact, would indicate that this ailment is not 

 the highly contagious foot-and-mouth disease which, once it is intro- 

 duced into a herd, quickly affects practically 100 per cent of the 

 cattle and hogs on all the farms to which the virus may be carried 

 by intermediate agencies. 



The result of this study of vesicular stomatitis suggests the ne- 

 cessity of inoculating horses with suspected material in any future 

 outbreak of disease bearing a resemblance to foot-and-mouth disease. 

 Finally, it must be apparent that in vesicular stomatitis we have a 

 disease more closely resembling foot-and-mouth disease than either 

 mycotic or necrotic stomatitis, and that Hutyra and Marek are cor- 

 rect in their opinion that a reliable differential diagnosis can be made 

 only after inoculation experiments and careful observation lasting 

 a number of days. 



In mycotic stomatitis portions of the lining membrane of the 

 mouth become inflamed, and in a few days it changes to a croupous 

 membrance which peels off, leaving a raw surface, while the thin 

 skin between the toes may also be inflamed. Swelling of the feet 

 and stiffness of the animal are frequently evident in mycotic stoma- 

 titis. The previous history of the case, the absence of its spread 

 to horses exposed to the infection, and the complete negative results 



