PRINCIPLES OF VETERINARY SURGERY 65 



organisms that must be blamed. The exact role of micro- 

 organisms in the causation of traumatic gangrene must, 

 however, not be misconstrued. They enter into the gangren- 

 ous process after some other action has interfered with the 

 nutrition of the affected area. Etiologically, they are 

 secondary; the bruise, the pressure, the Hgated artery, etc., 

 are the primary causes. 



Necrosis of the internal organs of animals occurs from 

 various causes. The presence of a foreign body in the ali- 

 mentary tract will often produce necrosis of a part of the 

 organ in which it lodges. In this manner the pharynx, the 

 oesophagus, the stomach, the rumen, the intestines, the 

 rectum, etc., often become the seat of serious fatal gangrenes. 

 Pharyngeal and oesophageal obstructions always, when not 

 removed, terminate in fatal necrosis at the seat of obstruction 

 from the continued pressure of the foreign body. Jones 

 of Illinois, found an extensive gangrene of the rumen, caused 

 from the accumulation of a large amount of binder-twine, 

 and analogous conditions are frequently reported of other 

 ingested foreign bodies. The pressure of tumors on blood 

 vessels or directly against organs may cause necrosis, and 

 severe infective inflammations are always liable to terminate 

 in softening from gangrene, abscess, or both. In the lungs, 

 haemorrhage, apoplexy, and pneumonia often terminate in 

 the death of a large area of the invaded tissue. A whole 

 lobe or even an entire lung may be found to be the seat of 

 a widespread gangrene. Here the condition is due both to 

 strangulated circulation and to putrefaction of the large 

 quantity of exudates exposed to the micro-organisms of 

 inspired air. The gangrenous lung follows, either a very 

 intense morbid process (apoplexy, pneumonia, etc.) or else 

 is predisposed by the general systemic enfeeblement of the 

 patient. 



2, Secondary or spontaneous gan^jrene refers to all of 



