160 SPECIAL EQUINE THERAPY 



MALIGNANT EDEMA 



Horses seem to be more susceptible to this disease than 

 other domesticated animals. It is an acute febrUe dis- 

 turbance characterized by the development of an edema- 

 tous and gaseous swelling at the seat of inoculation. The 

 infective organism is an anaerobic baciUus, which is said 

 to be universally present in the soil and in animal excre- 

 ment. Despite the general distribution of the bacillus, 

 the disease is comparatively rare. The infection develops 

 most commonly in puncture wounds, contusions, or in- 

 significant abrasions of the integument. Infection may 

 also result from injuries to the mucous membrane of the 

 mouth, nose, or eyes. The latter is rare. 



This disease runs a rapid and frequently fatal course. 

 After the period of incubation has expired, an extensive 

 swelling or edema develops at the seat of inoculation, 

 within a few hours. It is usually a rather smooth swell- 

 ing, blending gradually with the normal regions around 

 it. At the same time the animal gives evidence of 

 marked constitutional disturbance. The respirations are 

 rapid; the pulse increased in frequency so that it may 

 reach 60 or 70 beats per minute, and the temperature 

 may rise to 106 degrees or 107 degrees F. in the course of 

 the first few hours. 



When the swelling at the point of infection has fully 

 developed, it becomes emphysematous. When palpated it 

 crepitates. This is due to gas formation in the subcu- 

 taneous tissues as a result of the bacterial invasion and 

 the establishment of necrotic processes. At the point in 

 the swelling at which the disease is most active a gangre- 

 nous area develops. This area is frequently darker in 

 color than the remainder of the tumefied area, and, when 

 cut into, this part of the tumefaction proves to be non- 

 sensitive. At least, the affected animal gives no evidence 



