168 VETERINARY STUDIES 



106° or even 107° P. There is lameness in those cases which 

 show local swellings of the front or hind quarters. Some cases 

 are mild and misleading and diagnosis is not always easy. The 

 duration of typical cases is from a few hours to several days. 



Examination post mortem. — Examination of the carcass re- 

 veals a tumor filled with gas and dark, frothy blood with fetid 

 odor. The spleen is normal, and blood from the general cir- 

 culation is also apparently normal, clotting readily on expo- 

 sure to air. In such features as normal spleen, normally clotting 

 blood, and gas-filled tumor, the disease differs from true anthrax. 



Carcasses decompose and bloat rapidly and dark frothy blood 

 may ooze from the natural openings as in true anthrax. The 

 muscles involved in the local lesions are very dark when first 

 exposed to the air, and hemorrhagic conditions are common in 

 the chest and abdominal cavities. 



Prevention. — As soon as the disease appears, cattle under two 

 years of age should be promptly changed to another and pref- 

 erably higher pasture. If the young cattle have been on dry 

 food, their food then should be changed. Such feed may be 

 safely given to horses however. Blackleg carcasses should be 

 handled like those of anthrax, to avoid scattering the virus of 

 a serious disease. 



Vaccination is now satisfactory and thoroughly practical. 

 There are a number of commercial preparations on the market 

 that are quite reliable. The federal Bureau of Animal Industry 

 is supplying a blackleg vaccine, which is quite satisfactory. 

 Method of vaccination depends upon the kind of preparation 

 used. Directions usually accompany each shipment from any 

 of the reliable makers. 



Vaccination 



The vaccine. — The Bureau or government vaccine consists of 

 a brownish powder furnished in packets of ten and twenty-five 

 doses each. It is made from the muscle of animals affected with 

 blackleg, and is prepared by drying the muscle and grinding 

 and heating it to a temperature which lowers the virulence of 

 the bacilli, but does not destroy them. 



Preparation. — The needed outfit consists of a graduated hypo- 

 dermic syringe of about 5 c.c. capacity; rather short, stout 

 needles of good caliber, and sharp; a small mortar and pestle; 



