It happened Tuesday afternoon on County Road 23 in Coshocton County.
According to the sheriff's office, a neighbor saw a 150 pound male German Shepherd attacking the woman as he drove by the house.
That man did not want to comment.
But authorities say he was able to separate the two, put the dog in a kennel and start first aid.
The woman in her 30's was flown to Grant hospital in Columbus.
John Speaks, who lives nearby, says he's familiar with the dog now in quarantine at a veterinarian's office.
"He's always been very aggressive but he would never go beyond the road he guarded the yard and the house," said Speaks.
Speaks says the woman was lucky her neighbor stopped when he did.
"She's not a very big woman so if you're overpowered by a dog that big it would be a job for a good sized man," said Speaks.
Authorities say they don't know what prompted the attack.
(ABC 6 ON YOUR SIDE - May 1 2013)
