450 DISEASES OF CATTLE. 



Treatment. — In this disease remedies have thus far proved una- 

 vailing. Some writers recommend the use of certain drugs, which 

 seem to have been beneficial in a few cases, but a thorough trial has 

 shown them to be valueless. Others advise that the swelling be 

 opened by deep and long incisions and a strong disinfectant, such as 

 a 5 per cent solution of carbolic acid, applied to the exposed parts, but 

 this procedure can not be too strongly condemned. Since nearly all 

 those attacked die in spite of every kind of treatment, and in view of 

 the fact that the germs of the disease are scattered over the stables or 

 pastures when these tumors are opened, thus becoming a source of 

 danger to other cattle, it is obvious that su,ch measures do more harm 

 than good and should be put aside as dangerous. Bleeding, nerving, 

 roweling, or setoning have likewise some adherents, but the evidence 

 indicates that they have neither curative nor preventive value and 

 therefore should be discarded for the method of vaccination which 

 has been thoroughly tried out and proved to be efficacious in prevent- 

 ing the disease. 



Prevention. — The various means suggested under "Anthrax" to pre- 

 vent the spread or recurrence of this disease are equally applicable to 

 blackleg, and hence do not need to be repeated here in full. They 

 consist of the removal of the animals from the infected pasture to a 

 noninfected field, the draining of the swampy ground, the burial or 

 burning of the carcasses to prevent the dissemination of the germs 

 over vast areas through the agency of dogs, wolves, buzzards, and 

 crows, the disinfection of the stables and the ground where the ani- 

 mals lay at the time of death, and, if possible, the destruction of the 

 germs on the infected pastures. One of the most effective methods 

 for freeing an infected pasture from blackleg is to allow the grass to 

 grow up high, and, when sufficiently dry, to burn it off. One burn- 

 ing off, however, is not sufficient to redeem an infected pasture, but 

 the process should be repeated several years in succession. This 

 method, however, is in many instances impracticable, as few cattle 

 owners can afford to practice it, and the only means left for the pro- 

 tection of the animals is vaccination. 



Immunization by vaccination. — Three French veterinarians, Arlo- 

 ing, Cornevin, and Thomas, were the first to discover that cattle may 

 be protected against blackleg by inoculation with virulent material 

 obtained from animals which have died of this disease. Later they 

 devised a method of inoculation with the attenuated or weakened 

 blackleg spores which produced immunity from natural or artificial 

 inoculation of virulent blackleg germs. Their method has undergona 

 various modifications both in regard to the manufacture of the vac- 

 cine and in the mode of its application. Kitt, a German scientist, 

 modified the method so that but one inoculation of the vaccine was 

 required instead of two, as was the case with that made by the French 

 investigators. The vaccine prepared and distributed by the Bureau 



