474 DISEASES OF CATTLE. 



discharge is observed. The center of the swelling may appear soft 

 and jellylike, while the margin is tense, hot. and painful. The symp- 

 toms increase rapidly, resulting in coma and death. 



Lesions. — After death the fat and subcutaneous tissues surround- 

 ing the infected area are infiltrated with a yellow gelatinous material 

 containing an orange-colored foam, due to the presence of gas 

 bubbles. 



The muscles at this point are friable, spongy, and of a uniform 

 brownish tint, dissociated by gas and with a blood-tinged exudate. 

 This gangrenous tissue, when present before death, can be removed 

 without pain to the animal. The intestines are generally normal, 

 but, together with the peritoneum, they may be inflamed, and the 

 lungs are usually the seat of an edema. The spleen, liver, and kid- 

 neys retain their normal appearance, in marked contrast with anthrax. 



Differential diagnosis. — Unlike blackleg, this disease never appears 

 as an epizootic but in isolated cases. It may also be differentiated 

 from the former by the history of a recent parturition or surgical 

 operation, by the presence of an external injury at the site of the 

 swelling accompanied with a fetid liquid discharge, and the gan- 

 grenous appearance of the tumefaction. Man is susceptible to malig- 

 nant edema, but not to blackleg. Malignant edema may also be easily 

 differentiated from anthrax in that the blood and spleen are normal in 

 appearance, while in the latter disease the blood is dark and of a 

 tarlike consistency, and the spleen appears swollen, injected, and 

 softened. The local tumor in malignant edema contains gas bubbles, 

 which are absent in anthrax swellings. Inoculation experiments of 

 guinea pigs, rabbits, and chickens will also disclose the differences 

 among the above-mentioned three diseases, since all these species are 

 killed by the germ of malignant edema, only the first two species 

 l>y the anthrax l^acillus, while the guinea pig alone will succumb to 

 tlie blackleg infection. 



Treatment. — Treatment is chiefly surgical and consists in laying 

 the infected areas wide open by free incision, followed by a liberal 

 application of a 30 per cent solution of hydrogen dioxid and subse- 

 quently a 5 per cent solution of carbolic acid. Usually the disease 

 when observed has advanced to such an extent that medicinal inter- 

 ference is without avail. Preventive treatment is by far the most 

 desirable, and consists, essentially, in a thorough disinfection of all 

 accidental and surgical wounds, the cleansing of the skin, and the 

 exclusion of soil, filth, and bacteria during surgical operations of any 

 nature. Sheds, barns, and stables should receive a thorough applica- 

 tion of quicklime or crude carbolic acid wash after all rubbish has 

 been removed and burned. All dead animals should be burned or 

 deeply buried and covered well with quicklime. 



