What is the meaning of Heeler?

A gamecock that strikes well with its heels or spurs.

A quick runner.

A dog that readily comes to heel.

A dog used for cattle droving.

A dependent and subservient hanger-on of a political patron.

The rodeo performer who ropes the steer by its hind feet after the header has turned it.

A student journalist at Yale University.

Source: wiktionary.org