386 ACUTE EXANTHEMATOUS INFECTIOUS DISEASES 



form larger ones. The vesicles rupture in a very short time 

 and therefore are often not found even in the early stages of 

 the disease. "When the vesicle ruptures a red erosion per- 

 sists partially covered with grayish-white fragments of 

 mucous membrane. The erosions may become confluent 

 forming raw areas, particularly on the dorsum of the tongue, 

 as large as the palm of the hand, or the whole upper surface 

 of the tongue may be involved. Besides the tongue the 

 tooth surface of the lips, commissures of the mouth, and gums 

 may be attacked. In cattle the principal lesions occur on 

 the dental pad, lips, gums, and sometimes extending to the 

 muzzle. In fresh milch cows vesicles occasionally appear on 

 the teats probably due to infected calves sucking them. 

 Foot lesions have not been observed in these cases. In 

 horses the lips are swollen and itchy causing the animal to 

 rub them. 



With the eruption of the vesicles there is moderate fever 

 which rapidly subsides. As in all marked stomatites, a pro- 

 fuse flow of saliva occurs which hangs from the mouth in 

 thin strands or may be churned into foam. Sometimes the 

 first symptom noted of the disease is salivation. The 

 patients refuse food and in cattle the jaws are champed pro- 

 ducing a smacking noise as in foot-and-mouth disease. In 

 horses the patient frequently grits its teeth. Healing usually 

 occiu's in from eight to fifteen days. 



Diagnosis. — Infectious vesicular stomatitis in cattle may be 

 confused with the following: 



(a) Foot-and-mouth Disease. — ^To distinguish accurately 

 between foot-and-mouth disease and infectious vesicular 

 stomatitis requires close observation for several days and 

 inoculation tests. From the field standpoint the following 

 differences are noted: Horses are rarely infected with foot- 

 and-mouth disease. In the United States during the epi- 

 zootics of this disease no hoTses were attacked. While foot- 

 and-mouth disease spreads to swine on the same pastiure 

 infectious vesicular stomatitis does not. Sheep take foot- 

 and-mouth infection readily but do not seem susceptible to 

 infectious vesicular stomatitis. In infectious vesicular sto- 

 matitis the lesions appear to be continuous or progressive. 



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