HAPPY VALLEY -- Jayda Kempas, a 7-year-old who loves to play with Barbie dolls, was twirling on a tire swing and giggling with a friend when Titan leapt up and locked onto her left leg. The 90-pound pit bull mix yanked, and they both tumbled to the ground. Jayda's father, Steven Hehr, was smoking a Marlboro outside his friend's home in Happy Valley when he heard screams from the backyard. Titan, who was new to the home, usually stayed in the garage. But this time he had been left outside. Catching the first glimpse of his daughter, Hehr knew it...