282 BLACK LEG 



blood during life, but abundantly a few hours after death. 

 They are numerous in the local lesions. 



The duration of the disease is from one to three days. 

 Occasionallj' it is longer. The prognosis is grave. 



^ 204. Differential diagnosis. Black quarter is to be 

 differentiated from anthrax, the "corn stalk" disease, septi- 

 cemia hemorrhagica and various forms ot poisoning. Usually 

 the localized subcutaneous lesions are sufficient to differentiate 

 black quarter from these other affections. It often happens, 

 however, that post-mortem changes have so modified the car- 

 cass before it can be examined that the diagnosis is question- 

 able. In this and all doubtful cases or where only small por- 

 tions of tissue are sent for examination, it is necessary to 

 resort to a more definite method or methods, such as the mi- 

 croscopic examination, cultures and animal inoculation. 



1. Microscopic examination. Cover- glass preparations 

 made from the fresh tissues will ordinarih- exhibit the specific 

 bacteria. They are easily distinguished in case of anthrax, 

 black quarter and often with septicemia hemorrhagica, while 

 in the "cornstalk" disease and cases of poisoning character- 

 istic bacteria are not found. It is important to eliminate putre- 

 factive bacteria, when the animals have been dead for some 

 hours. 



2. Cultures. Ordinary culture media inoculated with 

 the tissues from a case of anthrax will give growths of the 

 anthrax bacterium, and from cases of septicemia hemorrha- 

 gica that of Bact. bovisepticum , but with the other two dis- 

 eases the3' will remain clear if uncontaminated. The black 

 quarter bacillus will grow on these media only when placed in 

 anaerobic conditions. In case of the "corn stalk" disease the 

 media will continue to be clear. 



3. A 7iinial inoculation. In guinea pigs inoculated in the 

 deeper subcutaneous tissues with pure cultures of black leg 

 bacteria or with bits of tissue from the affected area of another 

 animal dead from the disease, death ensues in from one to two 

 daj's. It is preceded by a raise of temperature, loss of appetite 



