142 Annual Report for 1905 of Royal Veterinary College. 
first established the non-identity of the two diseases, as they 
were found to be caused by two entirely different organisms ; 
but, as a matter of fact, swine fever and swine erysipelas are 
quite dissimilar affections, and can nearly always be readily 
distinguished in practice by their different symptoms and by 
the different conditions under which they occur. 
Swine fever is a purely contagious disease of the pig, and it 
never breaks out except where there have been opportunities 
for infection. Swine erysipelas may break out among pigs no 
matter how strictly they have been isolated ; and, although in 
some cases it attacks a large number of pigs simultaneously or 
in quick succession and may appear to spread by contagion, in 
most outbreaks only single cases of the disease are observed 
at a time, even when there has been no attempt to isolate 
the diseased animal. This fact was clearly brought out in the 
Report of a Departmental Committee of the Board of Agriculture 
in 1897. The fact that swine erysipelas frequently arises 
independently of contagion can only be explained by supposing 
that the germ which is the cause of the disease is one capable 
of multiplying in soil and dirt, and the slight tendency of the 
disease to spread must be ascribed to the fact that most pigs are 
but little susceptible to infection with it. 
In exceptional cases, of which the recent Cambridgeshire 
outbreaks furnish an example, the disease exhibits unusually 
virulent characters, and occasions serious losses. The cause of 
this is not well understood. Such severe outbreaks generally 
occur during the hot weather of summer or early autumn, and 
they may be caused by an unusually rapid multiplication of 
the bacilli in the soil or manure of the pigsty. It is also 
possible, however, that for some reason or another the bacilli 
suddenly acquire an unusual virulence, that is to say, an 
exceptional power of mischief for pigs, when they are taken 
into the alimentary canal. 
This acute form of swine erysipelas can, as a rule, be 
easily distinguished from swine fever by its more rapid course, 
and by the occurrence of peculiar, slightly raised, red or purple 
blotches on the skin. Death sometimes occurs so rapidly that 
poison is suspected. Post-mortem examination also makes it 
easy to distinguish between the two diseases, for the peculiar 
ulceration of the large intestine which is almost constant 
in swine fever is never met with in swine erysipelas. 
When an actual outbreak of swine erysipelas occurs, the 
best plan is to isolate the visibly diseased pigs and temporarily 
turn the apparently healthy out into a field, which is generally 
an easy matter at the season when outbreaks commonly occur. 
Before the sties are restocked they ought to be thoroughly 
cleaned and disinfected. 
