306 VETERINARY HYGIENE 



report of the Departmental Committee, which was issued in 1915, 

 stated in its general conclusions that " the continued prevalence 

 of swine fever appears to be due principally to its highly contagious 

 character, and the difficulty of its recognition by the pig owner 

 in its early stages and in its milder forms. To these causes must 

 be added the difficulty of completely tracing the place of origin and 

 the movement of pigs by which the disease has been spread. The 

 extirpation of the disease is practicable only by such drastic 

 measures of slaughter as would involve a prohibitive outlay, and 

 by such severe restrictions on movement as would be fatal to the 

 industry of pig keeping. Present circumstances, therefore, do not 

 encourage the view that the extirpation of swine fever can be 

 speedily accomplished." They recommended further that the 

 attempt to extirpate the disease by general slaughter should be 

 abandoned for the present, and that the immediate object of future 

 policy should be (a) to reduce mortality from the disease; (b) to 

 control the spread of the disease." 



Certain measures should be observed with a view to reducing 

 the prevalence of the disease. Curtailment, as far as possible, of 

 the store trade ; pig feeders should breed and feed their own stock. 

 Breeders should, if possible, keep their own boars and deny their 

 use to other parties. If fresh stock is brought in or sows return 

 from the boar, they should be kept in strict isolation for at least 

 a month. Carts, crates, nets and the like should not be lent to 

 neighbours. Visiting between one piggery and another should not 

 be encouraged. Rats should be exterminated, as they may act as 

 mechanical carriers of infection. Castrators should not be 

 employed ; owners or their attendants should castrate their own pigs. 

 The premises should be hygienically constructed and excreta and 

 yard washings must not be allowed to flow across the highway or 

 in close proximity to neighbouring premises. 



IMMUNITY. An attack of the disease leaves m the recovered 

 animal a very considerable degree of immunity, and an attempt has 

 been made in recent years to put this fact to practical use on a large 

 scale for the purpose of building up immune herds. Pigs can be 

 hyperimmunised by a series of injections of defibrinated blood taken 

 from pigs at the height of an attack, and such pigs yield a serum 

 which is very potent as a protective agent before infection, and 

 according to Hutyra and Koves* within six days after. It was 

 recommended by the Departmental Committee which reported in 

 1915 " that in order to reduce mortality, the use of protective serum 

 without avoidable delay in infected herds should be encouraged 

 * Journ. Comp. Path., 1917, Vol. XXX., p. 177, Abs. 



