His teeth were bared--he was more like a prodigious dog than a horse.

And those teeth closed on the back of the man's neck--or did they merely pinch his shirt ?--and then Dan was dragged bodily away from the wolf and thrown through the air by a flirt of the stallion's head.
Horrible! Buck Daniels shuddered and then he grinned shamefacedly in apology to himself.
"The three of 'em!" he grunted, and stepped closer to the fence to watch.
The instant the man was torn away by the intercession of the horse, the wolf regained its feet and rushed upon him; but Dan had landed from his fall upon his feet, with catlike agility, and now he dodged the rush of the wolf and the arrowy spring of the creature, and sprang in his turn towards the stallion.
The black met this attack by rearing, his ears flattened, his teeth bared, his eyes terrible to behold.

As the man raced close the stallion struck with lightning hoofs, but the blow failed of its mark--by the breadth of a hair.

And the assailant, swerving like a will-o'-the-wisp, darted to the side of the animal and leaped upon its back.

At the same instant the wolf left the ground with terribly gaping mouth in a spring for the rider; but Dan flattened himself along the shining back of his mount and the wolf catapulted harmlessly past.
After this failure the wolf-dog seemed to desire no further active part in the struggle, but took up a position to one side, and there, with lolling tongue and red-stained eyes, watched the battle continue.