She had to have one ear surgically re-attached, had several stitches to her head and lost a large chunk from one calf. One bite is understood to have been just a centimetre from the carotid artery in her neck.
Mr Logan said he called police and an ambulance after he got the dog off the woman and said he had visited her twice in hospital, where she had thanked him for saving her.
He said he immediately surrendered Luna [the dog] to animal control staff as he wanted him put down after the attack.
"I just did what I did when I saw Luna on her. I just jumped on top to protect her and Luna grabbed my arm. My neighbour Willie [Whyte] came over and I got Luna off the woman and took him inside," Mr Logan said.
He disputes that his other dog, Misty, also a Smithfield-cross, was involved in the attack, as suggested by council staff. He wanted the dog back after she was seized on Tuesday.
"They said witnesses said Misty was involved too, but only me and Willie saw it and we didn't see Misty joining in at all.
"She was running around in circles, but she didn't have a go," Mr Logan said.
Mr Whyte confirmed he did not see Misty attack the woman.
"My dog Luna attacked her so, fair enough, he should be put down and I wanted him put down, but Misty didn't do anything wrong and I want her back," Mr Logan said.
"I'm really sorry for what happened to the lady and I never intended it to happen at all, but she was dressed in a brown sheepskin coat with tassels and fluffy bits hanging off it and with brown leather boots on.
"He [Luna] was almost in a frenzy," he said.
Luna had been impounded once before, along with his mother, after they attacked a neighbour's pet rabbits, but he had never attacked people before, he said.
Mr Logan claimed the mental health worker had been to the property the day before the attack and knew there were two dogs there.
He said she had arranged to visit between 10.30am and 11am the following day and he said she told him she would telephone ahead of her visit.
But the woman arrived about 10.10am, didn't ring ahead and went straight on to the property, despite two signs warning there were dogs, he said.
She was attacked before she got to the door.
No charges have been laid against Mr Logan at this stage but the matter is being investigated by animal control staff.