The time will come to each of us to chuck one's weight around; to exhibit a periods of ostentation, influence or power.
Source: Funk, Charles
dog eat dog
ruthless competition or self-interest
Source: wordreference.com, The Collins English Dictionary
a dog's chance
no chance at all
Source: wordreference.com, The Collins English Dictionary
big dog
important person
Source: Bertram, Anne (Pig's Eye)