It seemed to delight her when such cars slackened speed or swerved, in order not to kill her.
Now, as she whizzed backward, her vibrant muzzle a bare six inches from the shiny buffer, one of her flying feet slipped in a mud rut.

Her balance gone, she tumbled.
A collie down is a collie up, in less than a second.

But there was still less than a second's space between to overthrown Lady and the car's front wheels.
The boy slammed on the emergency brake.

Through his mind ran the formless thought of his fate at the hands of his employer when he should return to the store with tidings that he had run over and killed a good customer's costly collie; and on the customer's own grounds.
In that single breathless instant, a huge mahogany-and-snow shape flashed forward, into the path of the machine.
Lad, following his mate, had tried to shoulder her aside and to herd her too far back from the drive for any possible return to the danger zone, until the car should have passed.

More than once, at other times, had he done this.