The Manatee County Sheriff's Office said the girl grabbed the pit bull by its collar around 4:20 p.m. Monday after it got away from her and fled into Pride Park in Bradenton, the Bradenton (Fla.) Herald reported Tuesday.
The girl said a woman, later identified as Catherine Warren, 57, pulled up in her car and told her it was obvious the dog was being abused and needed to be taken away.
Warren pushed the girl to the ground and fled with the dog, deputies said.
The deputies said they later located Warren and arrested her on a charge of robbery. She was taken to the Manatee County Jail.
The sheriff's office did not say whether the dog was returned to the girl.