Barry is simply a man who is closer akin to the brute forces in nature.

See! By the eternal heavens, he's dragging that beast--that dumb beast--back from the door of death!" Barry had ceased his rapid manipulations, and turned the big dog back upon its side.

Now the eyes of Black Bart opened, and winked shut again.
Now the master kneeled at the head of the beast and took the scarred, shaggy head between his hands.
"Bart!" he commanded.
Not a stir in the long, black body.

The stallion edged a pace closer, dropped his velvet muzzle, and whinnied softly at the very ear of the dog.

Still, there was not an answering quiver.
"Bart!" called the man again, and there was a ring of wild grief--of fear--in his cry.
"Do you hear ?" said Byrne savagely, at the ear of the girl.