PRINCIPLES OF VETERINARY SURGERY 309 



forms. They include simple abrasions in which only the 

 epidermis is affected, and erosions frequently seen in horses 

 that fall and drag a portion of the body along the ground 

 for a variable distance. Since the body inflicting the injury 

 is blunt it is essential that it take effect on an anatomical re- 

 gion with a resisting or bony base. Thus, in wounds of 

 the orbit caused by falls, the skin is crushed and divided 

 from within outward. Contused wounds may also be caused 

 by blows with a stick or whip handle, or from prolonged 

 ciecubitus. The physiognomy of these wounds varies with 

 their nature. In slight ones there is generally no hsemor- 

 rhage, but the pain may be rather intense, or even acute. 

 When the traumatism has been very violent the disturbance 

 produced may be considerable. The skin may be loosened 

 over a large surface, the tissues may be crushed and torn 

 and important organs may be exposed. But in spite of these 

 serious disturbances the haemorrhage is nearly always in- 

 significant, not only because of the crushing of the blood 

 vessels but also on account of the traumatic shock which 

 is always accompanied by a fall in the arterial pressure due 

 to enfeeblement of the cardiac impulse. 



Contused wounds were formerly of a very formidable 

 character. Most of the infective morbid processes were as- 

 cribed to them. Their irregularity, their extent, their deep- 

 seated nature, the variety and number of tissues affected, 

 the abundance of coagulated blood, and of accumulated se- 

 rum, and the difficulty often experienced in cleansing them, 

 made them veritable nests of infection. Gangrenous septi- 

 caemia, pyaemia and tetanus so frequently resulted that they 

 might have been referred to as "classic soils for complica- 

 tions." 



PATHOLOGICAL ANATOMY.— Their anatomo-path- 

 ological characteristic is the absence of precise limits. The 

 contused wound is bounded by bruised, mangled and irreg- 



