Annual Report for 1913 of Royal Veterinary College. 353 
Facts which stand beyond dispute with regard to well- 
prepared anti-swine fever serum are : — 
1. A moderate dose of the serum when injected under the 
skin of a healthy pig will confer on it a high degree of immunity 
against swine fever. 
2. The immunity thus conferred declines steadily, and 
unless a further dose of serum be given it disappears in three 
or four weeks. 
3. When injected during the period of incubation, or at the 
very outset of the visible illness, the serum exerts curative 
effects, but it cannot be relied upon to check the course of the 
disease during its advanced stages. 
Two different methods of employing the serum have been 
recommended and practised, and these must be considered 
separately. 
1. The simple serum method . — Under this system when an 
outbreak occurs all the visibly diseased pigs are slaughtered, 
and each of the apparently healthy animals is given a dose of 
serum. Remembering an important fact already stated, viz., 
that the immunity conferred by serum only lasts for three or 
four weeks, one might have reasoned that this could not be an 
effective method of dealing with an outbreak, for one would 
have supposed that at the end of a month events would simply 
resume their normal course, the disease attacking the pigs 
which had now lost all their immunity. But experience shows 
that this is not what usually happens. According to the 
Hungarian experience in about half the cases the outbreak may 
be definitely cut short by the serum, while in the remaining 
outbreaks cases continue to occur afterwards. In those out- 
breaks in which the disease appears to be definitely stamped 
out by serum treatment it is probable that many of the pigs 
have actually become infected before the serum immunity has 
been lost,, and have thus passed through a mild unnoticed attack 
of the disease, in consequence of which they are immune for 
a long period afterwards. 
It is important, however, to notice that in many cases the 
disease and the deaths continue after the whole of the surviving 
pigs have been treated with serum. Thus, in Hungary, in 
1909 — 1911 (in which period more than a million swine were 
thus treated), statistics collected with regard to 695 outbreaks 
showed that in 597 the deaths after treatment averaged 4*2 
per cent., and that in the remaining 98 outbreaks they averaged 
407 per cent, of the pigs. 
Serum and virulent Wood method . — Under this plan each 
apparently healthy pig at the scene of an outbreak is given a 
dose of serum and at the same time a dose of virulent blood, in 
the expectation that this will cause each animal to pass through 
YOb. 74. N 
