A) 
VESICULAR STOMATITIS OF HORSES AND CATTLE 3 
aphthosa, erosive stomatitis, sore mouth, “ blue tongue,” and pseudo 
foot-and-mouth disease. : 
ETIOLOGY Y 
Vesicular stomatitis is Bae by a filter-passing virus, which has 
been shown to pass through such bacteria-retaining filters as the three 
grades of Berkefeld, designated by the letters V, N, and W, and of 
the Chamberlain, known as L 3 and L 7. 
The virus is contained in the contents of vesicles which develop 
in the course of the disease in the epithelium covering them and also 
in the blood during the febrile stage and for a short period follow- 
ing. It has not thus far been demonstrated to occur in the milk of 
cows except as a contaminant from vesicles, which sometimes form 
on the teats. However, the work dene to determine this has not been 
sufficient to lead to conclusive results. The virus disappears from 
the mouth of the affected animals within a few days after the rupture 
of the vesicles. 
Though little work has been done to determine the resistance of the 
virus to sunlight, drying, and disinfectants, the indications are that 
it is rapidly destroyed by these means. However, fragments of the 
epithelial coverings of vesicles kept in a moist state either in 50 per 
cent glycerin or without it, placed in test tubes, sealed with paratfiin, 
and kept in the dark in the ice box, have been found in some 
instances to contain active virus at the end of a month. 
Virus kept alive for more than four years, by successive passages 
through guinea pigs, still appeared to have lost little of its virulence. 
On the other hand, the disease often appears to die out in naturally 
infected herds without infecting more than a small proportion of the 
animals, 
PLURALITY OF TYPES OF VIRUS 
In 1925 the Bureau of Animal Industry discovered the existence 
of two types of vesicular stomatitis in the United States, which 
appear to be indistinguishable clinically, just as there has been 
found to be three types of foot-and-mouth-disease virus in Europe. 
The general characteristics of the two viruses seem to be the same, 
but one type of virus does not immunize against the other, although 
it does against itself. An animal recovering from one type might 
suffer from a fresh attack of the disease caused by the other within 
a few weeks, whereas it would be immune to the same type for 
months and possibly years. 
One of the two types of virus was found to be responsible ‘for an 
outbreak of vesicular stomatitis in the Middle West early in 1925, 
another in New Jersey late in 1925, and a third outbreak in Ala- 
bama in 1929. 
PATHOGENICITY 
Under natural conditions the disease is transferable to cattle, 
horses, and mules, but in the several outbreaks of the disease that 
have occurred in this country no hogs or sheep have been observed 
to have become affected with the disease through natural exposure. 
Hogs, however, may be infected by inoculation, as may also guinea 
pigs. but the latter likewise do not contract the affection by natural 
exposure. 
