4 BULLETIN 662, IT. S. DEPARTMENT OF AGRICULTURE. 



case of vesicular stomatitis in a mule and with which suspicious 

 symptoms of the disease were induced in other mules/ were ob- 

 tained for study. With this organism, which proved to be a faculta- 

 tive anaerobe and very slow to develop on any medium, we were 

 unable to infect horses or calves by direct inoculation of large 

 amounts of the culture. Moreover, the employment of this organ- 

 ism, as well as several other different organisms, as an antigen in the 

 complement-fixation test failed to give positive results with sera from 

 either immune horses or immune cattle. 



SYMPTOMS AND LESIONS. 



The first phenomenon of vesicular stomatitis consists in the 

 formation of reddened patches on the buccal mucosa, especially of 

 the tongue. These are quickly succeeded by vesicles or blisters of 

 grayish-red color only slightly elevated and of various sizes from a 

 dime to a silver dollar, filled with clear or yellowish serous fluid. 

 These blisters may be isolated, but frequently they coalesce to form 

 a large vesicle. They usually rupture in a very short time, which 

 accounts for their not being recognized at times even in the early 

 stages of the disease. The rupture of the vesicles results in exposing 

 the raw underlying surfaces, which appear as reddened erosions with 

 the grayish-white fragments of the torn mucous membrane of the 

 preexisting vesicles still attached to the irregular borders like a 

 fringe. These erosions may become confluent, varying from the 

 size of a dime to that of the palm of the hand, and may even involve 

 practically the entire upper surface of the tongue in horses. Heal- 

 ing varies, but usually occurs quite rapidly in from 8 to 15 days in 

 uncomplicated cases. 



While these lesions in horses are principally confined to the upper 

 surface of the tongue, they may involve the inner surface of the 

 lips, the angles of the mouth, and the gums. In cattle, on the 

 other hand, the tongue does not appear to be so extensively affected, 

 and lesions may also occur on the hard palate, lips, and gums, some- 

 times extending to the muzzle and around the nostrils. Often the 

 lips of the horse are swollen and itchy, which causes the animal to 

 rub the muzzle against any near-by object. In a very few cases 

 fresh cows have shown similar lesions on the teats when their infected 

 calves had been sucking them, but no feet lesions have been observed 

 in these cases. 



Immediately before or simultaneously with the appearance of 

 the vesicles there is present a moderate rise of temperature, which 

 rapidly subsides. A more or less profuse flow of saliva follows, 

 which dribbles from the lips and consists of a thin, stringy, or frothy 

 fluid. Not infrequently the presence of salivation is the first indica- 



i American Journal of Veterinary Medicine, vol. 12, No. 4, April, 1917, p. 22 



221. 



