Dog eat dog is an informal expression which means ruthless competition, and looking out for oneself, as in "It's a dog eat dog world."In literature:
Dog Eat Dog , a 1995 novel written by renowned crime-novelist Edward Bunker.
Dog Eat Dog , a 2004 campus novel by Niq Mhlongo set at the University of Witwatersrand.
Dog Eat Dog & Vice Versa , a 2006 marketing book written by marketing guru Jerry Rossi.
In film and television:
Dog Eat Dog , a 2001 film
"Dog Eat Dog", an episode of Crime Scene Investigation
Dog Eat Dog , a game show aired on the BBC
Dog Eat Dog , a game show aired on NBC in the United States
Dog Eat Dog films, Michael Moore's production company
Dog Eat Dog , a musical group
Dog Eat Dog , a 1985 album by Joni Mitchell
Dog Eat Dog , a 1992 album by the American rock band Warrant
"Dog Eat Dog", a song by Ted Nugent on his 1976 album Free For All
"Dog Eat Dog" , a song by AC/DC on both the Australian and international versions of their 1977 album
Source: http://en.wikipedia.org/wiki/Dog Eat Dog