Cause
Fight wound infections are caused by a bite wound from another animal -- usually, another cat. Unneutered male cats are the most likely to develop an abscess because they tend to roam around outdoors and get into fights to defend their "territory."  There is a tremendous amount of bacteria in the mouth of a cat, so anytime a cat bites a human or another animal, there is a very good chance that the bite will become infected.  Cats with bite wounds or an abscess should be taken to a veterinarian; likewise, humans that receive a bite should seek immediate medical attention.