538 GENERAL THERAPEUTIC MEASURES 



in meat-piece broth, and its injection is not accompanied by the least 

 danger, because the filtrate is quite germ-free." 



The successes attained in the J^'ar East with blackleg filtrate have 

 been duplicated in the United States. The statistical data available on 

 over one million vaccinations prove conclusively the effectiveness of the 

 product, and in consideration of the many advantages of a germ- free fil- 

 trate its superiority for the control of the disease in cattle is apparent. 



The greatest advantage of the blackleg filtrate is that it does not 

 contain the blackleg germ in any form and therefore, cannot induce the 

 disease under any circumstances. At the same time, it possesses all of 

 the immunity producing properties of the vaccine, so-called aggressins 

 (extracts), and liquid culture vaccines. 



Blackleg filtrate should not be confused vi'ith blackleg serum, which 

 confers only a passive immunity, lasting but a few weeks ; whereas the 

 blackleg filtrate affords protection to the animals for about one year. 



Blackleg filtrate is prepared by cultivating the blackleg bacillus in a 

 special medium until the maximum growth is obtained and the liquid 

 becomes thoroughly charged with the products of the germs. The prod- 

 uct is then suitably preserved and filtered through porcelain which re- 

 moves all the germs. It is then properly standardized and carefully 

 tested on animals for potency and sterility. 



Germ free extract (natural aggressin) is obtained from animals ar- 

 tificiallj' infected with the disease and after death the fluids of the affected 

 muscles are extracted by pressure. After filtering, testing and suitably 

 preserving the filtrate it is ready for use. 



Blackleg vaccine, powder and pellet form, is prepared from the af- 

 fected muscle of an animal artificially infected with blackleg. The 

 muscles of the involved part are cut into strips, dried and pulverized in a 

 drug mill. The powder is then mixed with distilled water into a paste, 

 filled into shallow pans and placed in an attenuating oven wliere it is 

 subjected to a temperature of 95° C. (203° F.) for a period of six hours. 

 The attenuated material is then ground' into a iDowder which is prepared 

 into either pellet or powder form. 



The product known as liquid blackleg vaccine represents attenuated 

 cultures of the blackleg organisms. 



Anti blackleg serum is obtained from horses or cattle which have been 

 injected with cultures of blackleg, at first with small doses, which later 

 are increased until as high as 500 mils are injected intravenously. The 

 serum is then standardized on guinea pigs for its protective value against 

 a definite amount of virus. 



In order to minimize the losses from this disease it is essential not 

 to defer vaccination until its actual appearance among the animals. Sus- 

 ceptible stock should be vaccinated periodically and systematically; its 

 occurrence cannot be controlled otherwise. 



A further advantage to be gained by such practice lies in the preven- 

 tion of reinfection of the soil through the discharges of sick animals and 

 from improper disposition of carcasses, thereby "wearing out" the infec- 

 tion from the soil. 



CANINE DISTEMPER. 



Canine distemper Q/StfffegEfl^)iiAfefO)S®/iffeease of dogs accompanied 

 by fever and an acute inflammation of the mucous membranes. The 



