Ruthlessly competitive and often cruel: dog-eat-dog world of New York City(1850s+)
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with dog eat dog
Ruthless acquisition or competition, as in With shrinking markets, it's dog eat dog for every company in this field. This contradicts a Latin proverb which maintains that dog does not eat dog, first recorded in English in 1543. Nevertheless, by 1732 it was put as “Dogs are hard drove when they eat dogs” (Thomas Fuller, Gnomologia).