MALIGNANT EDEMA , 161 



of pain, from the knife stroke. In grave cases, or those 

 which are not favorable, the tumefaction may spread over 

 a considerable portion of the body. In certain sections 

 of the South, malignant edema is frequently seen affecting 

 the region of the parotid gland. The cases are nearly 

 always fatal. 



Differentiation. The symptoms of malignant edema 

 must be differentiated from subcutaneous emphysema 

 following injuries, and from septicemia following an 

 injury. Subcutaneous emphysema resulting from in- 

 juries, and which is merely caused by suction created 

 from movements of the thorax during breathing, is not 

 accompanied by any systemic abnormalities. The tem- 

 perature is normal, and the horse is not depressed or 

 dejected. Usually, the wound in company with subcu- 

 taneous emphysema is rather large and gaping. The 

 wound in cases of malignant edema is nearly always a 

 small puncture wound, and in most cases can not even be 

 demonstrated. Septicemia resulting from wound infec- 

 tion differs from malignant edema in the fact that crepi- 

 tation is absent in the swelling of the former. Neither 

 does septicemia show the gangrenous area at the active 

 point in the swelling. 



Prognosis. This is unfavorable in probably fifty per 

 cent of all cases, and in over ninety per cent of the serious 

 cases. Death may come within four or five hours in 

 some of the most severe cases. In moderate attacks it 

 may come in a day or two, while mild cases recover after 

 variable periods of time. Cases that live over forty-eight 

 hours may be considered favorable after the lapse of such 

 a period of time. 



Treatment. The treatment of malignant edema is not 

 very satisfactory in results. Some practitioners have 

 made reports of good results from the use of oxygen gas. 

 A small oxygen tank, such as is used by some in the treat- 



