What makes the man turn animal on a Rugby field when off it he’s…gentle and softly spoken. Clark explains: Rugby league is a game of survival. It’s dog eat dog … (Longman)
A negative view of marketing is the "dog eat dog" view where the school can only gain by putting another school at a disadvantage or loss. BNC
For 20 years after World War Two it seemed possible that the dog eat dog "survival of the fittest" brand of free market capitalism had been supplanted by a social contract between employers and workers, with only occasional mediation by the state. BNC