244 PRINCIPLES OP VETERINARY SCIENCE 



Within twenty-four hours the edges of the wound adhere with 

 blood, afterward a fluid-like substance, wound cement, performs 

 this function. The surface of the wound remains dry. In four 

 to eight days definite union results, and a relatively small scar is 

 the only sign left of the wound. . • 



(2) Healing by secondary intention is characterized by the 

 production of granulation tissue, and is generally accompanied 

 by pus formation as a result of infection from pus-producing organ- 

 isms. Old wounds, infected wounds, and wounds with loss of 

 substance heal under this method. The granulation compensates 

 for the destroyed tissue, and also forms an important protection 

 against the entrance of any infectious material into the blood- 

 stream whence it might be spread to all parts of the body. It is a 

 good sign when granulations appear in a wound, for there is then 

 no further danger from absorption of poisons. This function of 

 granulation tissue has been demonstrated by placing pure cul- 

 tures of anthrax bacilli on a granulating wound of a sheep. The 

 disease did not develop, even though sheep are very susceptible to 

 anthrax. 



(3) Abnormal wound healing implies the formation of excessive 

 amounts of granulation tissue, termed "proud flesh" or "grapes," 

 a complication often seen in wounds around the hoof-head. It 

 occurs when the process of healing is too rapid. The cause is ex- 

 cessive irritation from mechanical irritants, such as licking and 

 rubbing the part ; or chemical antiseptics, such as copper sulphate 

 injudiciously used; or bacteria in great numbers. Proud-flesh 

 formation must be stopped before the wound will heal properly. 



Scars result from the newly formed connective-tissue cells, 

 which contract with age and force the blood out of the parts, 

 leaving the typical white appearance. A scar contracts for a 

 long time after healing has taken place. This accounts for the 

 pulling and "stitches" felt in healing and healed wounds. If 

 the end of a severed nerve becomes caught in the scar-tissue 

 when the wound heals, pain may be felt for years, but is always 

 referable to the normal ending of the nerve. 



SPECIAL KINDS OF WOUNDS 



Galled shoulders result from improperly fitted collars, too 

 large collars, collars too wide at the top, or an accumulation of 

 dried sweat and dirt on the collar or collar pad. The first step 



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