CHAPTER V. 

 SUBCUTANEOUS EMPHYSEMA. 



By subcutaneous emphysema is meant the condition produced by 

 the entrance of air or gas into the subcutaneous and interstitial con- 

 nective tissue. Emphysema may remain localised or it may become 

 generalised, according to the nature and extent of the lesion which 

 causes it, and the points where emphysema is developed. Subcu- 

 taneous emphysema is common in the sheep and ox. 



Symptoms. Sometimes the symptoms of subcutaneous emphysema 

 are extremely well defined. They consist in the presence of diffuse or 

 limited crepitant swellings which may appear at various points — in the 

 flank or the entrance to the chest; more rarely in the region of the 

 elbow, etc. 



The limits of crepitation may be ascertained by palpation, while 

 percussion produces a peculiar abnormal sound. The subcutaneous 

 tissue and very often the interstitial tissue appear as though 

 blown out. 



Emphysema may be generalised. Such an accident is rare, but 

 may occur in the ox as well as in the sheep and goat. 



Provided the emphysema remains confined to the subcutaneous 

 tissue, the animals are not necessarily in danger. Where, however, 

 it also extends to the interstitial tissue, and particularly if the cause 

 to which it is due continues, death may result in a very short time. 

 This occurs, for example, when the emphysema extends into the 

 mediastinum, and thus gains the pleura and lung. 



The symptoms of emphysema are then complicated with respira- 

 tory and circulatory disturbance and with signs of asphyxia. 



Causation. Subcutaneous emphysema may be produced in many 

 different ways. 



If, for example, in puncturing the rumen the canula be carelessly 

 withdrawn so that the skin is slightly separated from the subjacent 

 tissues, gas may pass from the rumen into the channel produced by 

 the instrument. It then becomes distributed throughout the sub- 

 cutaneous tissue, and if the cutaneous opening is displaced its escape 

 is confined to the connective and interstitial tissues in the region of 



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