Isabelle De Maximy, 43, says she was speaking to a neighbour in Belgravia Gardens, when the animal, which she believed was an American pit bull - a banned breed - bounded out of the lady's home and pounced on her.
She said: "It went straight to me and attacked me. It knocked me to the floor and started biting into my leg and wouldn't let go for at least 20 seconds.
"He was dragging me and just shaking his head back and forth, left to right, and pulling me."
Ms De Maximy said her neighbour was shouting at the dog but was too scared herself to intervene.
She said: "After a while the dog went back into the house and I managed to crawl back into my house. My children were traumatised. My daughter was in tears knowing what had happened and I was on the floor in pain."
Her daughter called an ambulance and the school worker eventually ended up in East Grinstead Hospital where she underwent surgery and stayed for a week.
The attack has left her with six scars and 20 stitches on her thigh, and the keen runner is now too scared to exercise in the park like she used to.
She said: "I don't walk properly and it's still painful. I've got pain everywhere in my leg.
"I feel really scared of dogs now. I'm even scared to put my bins out."
Ward councillor Cllr Julia Fletcher said: "It's really shocking that such a vicious attack on a quiet residential street.
"I hope the owner is not allowed to have another dog in the future."
A spokeswoman for Lewisham Police confirmed they had been called at 2.10pm on May 27. She said: "Officers seized the dog from the location and it is subject to an examination to determine its breed
"The suspect, who was not the owner of the dog, was cautioned but enquiries are still ongoing in relation to any offences the controller of the dog at the time may have committed."
(This is Local London - June 10, 2013)
