03/23/2012 at 04:00 PM EDT
When a 17-year-old St. Petersburg, Fla., girl did a good deed by taking a shelter dog for a walk, she didn't think the pup would return the favor.
But Mabeline, a Rhodesian Ridgeback mix, did – and then some. On a recent Saturday afternoon, the volunteer took the then-homeless dog for a standard walk near Friends of Strays animal shelter.
A registered sexual predator attacked the girl, grabbing her by the hair and pinning her down on the ground.
That's when Mabeline, who had never before displayed any aggression or guard dog tendencies, started barking in the volunteer's defense. The attacker backed off, and the girl was able to flee.
Since the incident, Mabeline has found a forever home with new owner Mary Callahan, who told Tampa Bay's WTSP 10 News
that upon discovering what Mabeline did, "I looked at my dog and I thought, 'You are a hero.'"