The dogs were ''barking furiously and frothing at the mouth'' by the time he reached them.
He swung at them with the pick axe handle and shouted at them, which convinced the dogs to run back home, inside the open front door and upstairs.
''I stood at the front door. I shouted: 'You come down here and I'll bloody whack you'.''
The women were taken to nearby Southland Hospital with dog bites.
Victim Jennifer Shaw (65), who lives several streets from where the attack happened, was last night nursing a dog bite to one knee and a graze to the other.
Her friend Lorraine Turner, in her 70s, was recovering at home with a broken arm and multiple dog bites after being discharged from hospital yesterday.
Both woman were in a state of shock.
''We were just out for a walk ... I just don't know why [the dog owners] didn't have their gate shut,'' one woman said.
As for walking around the neighbourhood again, she said: ''I will think about it in a wee while''.
A woman at the address where the dogs lived declined to comment.
Both animals, understood to be pig-hunting dogs, were handed over by the owners to animal control officers.
Only one of the seized dogs was registered.
Several neighbours called emergency services and rushed to the injured women's aid.
Angela Jackson took towels to help stop the bleeding of the more seriously injured woman.
''She was lying on the ground and couldn't get up.''
The dogs and their owners had only moved into the property, on the corner of Henderson and Albany Sts, a few weeks ago.
Invercargill City Council environmental health and compliance manager John Youngson confirmed yesterday frequent complaints had been received about the dogs.
The property had been visited last week and the dog owner spoken to. But there had been nothing to suggest the dogs would act as they had, he said.
Neighbours told the Otago Daily Times the dogs roamed the area frequently, barking and chasing cars.
Dylan Shearer, who lives opposite, said the dogs could open a gate across the driveway by themselves and were ''always out''.
Gerard Jackson said he saw one of the dogs standing on his front doorstep a few days ago. It was large and intimidating, he said, but left when he shouted at it.
Mr Youngson said the council was reviewing bylaws concerning dogs.
Invercargill had a ''dog control problem'' and Mr Youngson acknowledged the latest incident would prompt calls to ban certain dog breeds.
''If you saw these dogs in the street, you would just think they were nice-looking dogs.''
The council was exploring legal action, Mr Youngson said.
He praised the actions of Mr Castellani and fellow neighbours, because ''it would have been far more serious, from the pictures I have seen.
''If it was a prolonged attack, I would hate to think what had happened.''
