PREVENTIVE MEDICINE 309 



of 17-4 per cent, in favour of the pigs on premises where serum 

 treatment was applied, notwithstanding the fact that the deaths 

 on these premises included a very considerable number of pigs, 

 which for various reasons were not treated." 



" Certain limitations were put upon the results obtainable from 

 serum treatment by the conditions under which it has to be applied 

 in practice. The limitations arise mainly from the Authorities 

 being dependent upon owners for immediate notice of suspected 

 outbreaks, and from the fact that it is seldom either practicable 

 or useful to apply serum treatment before disease has appeared 

 on the premises ; on an average, about 30 per cent, of the pigs were 

 dead or in the grip of infection before opportunity arose for treat- 

 ment. Notwithstanding these limitations, it appears that serum 

 treatment achieved very considerably better results at infinitely less 

 cost than other methods previously tried for dealing with swine 

 fever. It would also appear that the effect of these limitations 

 could be lessened by earlier reporting." 



The chief advantage of the use of serum is that it enables one 

 to save some pigs alive, and in particular valuable breeding animals. 

 Thus at the end of the outbreaks (2100) mentioned in the report 

 for 1916, among those untreated with serum only 34-2 per cent, 

 of the breeding stock were left alive, while among those treated 

 66-8 per cent, were freed. It is difficult to apply the serum to 

 suckers owing to the fact that these are born at odd times and 

 because for the first few weeks they do not get the chance of 

 acquiring an active immunity after receiving serum, and it is often 

 not possible in practice to give them more than one dose. The 

 mortality among suckers even after treatment, therefore, tends to 

 be high. 



CONTAGIOUS SWINE PNEUMONIA. 



In Germany there were first described outbreaks of a disease 

 to which the name " Schweinseuche " was given and which is 

 known in America by the name of " swine plague," and in which 

 pneumonia is said to be a constant lesion. In this country cases 

 of pneumonia occur in pigs sporadically and also quite commonly 

 as complications of swine fever, though only in rare cases are they 

 actually caused by the swine fever organism. 



It is possible that the cases of Schweinseuche are in reality 

 sporadic in origin and due to the same cause exerting its action 

 on a number of pigs at the same time. The causal agent is a 

 pasteurella which is capable of existing as a saprophyte in the 



