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VESICULAR STOMATITIS OF HORSES AND CATTLE 9 
able from them. Furthermore, instead of increasing in virulence as 
it passes through the herd and infecting practically every animal 
in it, vesicular stomatitis tends to die out before it has infected a 
very great proportion of them. 
The percentage of animals infected in each of the herds of cattle, 
and the history of exposure without transmission of the disease ex- 
cept 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 neces- 
sity of inoculating horses with suspected material in any future out- 
break of disease bearing a resemblance to foot-and-mouth disease, 
as this appears to be the only present method of promtly differen- 
tiating between it and vesicular stomatitis. 
Finally, it must be apparent that vesicular stomatitis is a disease 
more closely resembling foot-and-mouth disease than either mycotic 
or necrotic stomatitis, and that Hutyra and Marek are correct 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 lning membrane of the 
mouth become inflamed, and in a few days it changes to a croupous 
membrane 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 
obtained by the inoculation of calves, distinguish between this dis- 
ease and vesicular stomatitis. Lastly, mycotic stomatitis occurs in 
only from 10 to 15 per cent of the cattle in a herd, usually late in 
the summer or early in the fall after a dry spell, and it does not 
run a regular course. 
Necrotic stomatitis may be distinguished from vesicular stoma- 
titis by the fact that while it affects cattle and especially calves, it 
may also involve pigs and sheep, but its spread among the animals 
of a herd shows a much lower degree of infectiousness than vesic- 
ular stomatitis. The characteristic lesion of the latter is the appear- 
ance of blisters containing a serous fiuid on the mucous membrane 
of the mouths of the affected animals. In necrotic stomatitis blis- 
ters are never formed, destruction of the tissues occurring from the 
beginning and being followed by the formation of yellowish, cheesy 
patches principally found involving the lining membrane of the 
mouth, especially the tongue and cheeks. The cause is Actenomyces 
necrophorus (Bacillus necrophorus). 
In horses vesicular stomatitis must be differentiated from con- 
tagious pustular stomatitis, and this is not difficult. In the latter 
disease there are no simple erosions, but. instead there are raised 
nodules on the mucous membrane of the mouth. These nodules 
suppurate and liquefy in the center, causing the conical surfaces 
to slough, resulting in the formation of pustules or ulcers, from 
which the name of the disease is derived. The location of the 
