Sunbury Square barista Christina Moyle was visiting the Scott St home of a friend on August 29 when the vicious attack happened.
Mrs Moyle, 42, was returning from the bathroom when the dog, named Bullet, burst out of a bedroom before leaping at her throat.
"It was running fast and jumped up and put its two front legs on my shoulders and bit me on my face," she said.
"It's jaw was locked on to my nose, mouth and chin. I punched the dog with my right fist as hard as I could. The dog let go ... It felt like my face was hanging down and torn apart, there was blood everywhere."
Mrs Moyle needed more than 100 stitches to repair her face and spent four days recovering at Royal Melbourne Hospital.
She has had trouble sleeping and has had nightmares every night.
"I don't know how I am going to get over this. I see dogs in the street and I am terrified of them.
"When I see myself in the mirror I get very upset, I think I look like an ugly monster."
Hume Council's city infrastructure director Steve Crawley said council officers and police seized and impounded two dogs from the Sunbury property on August 30.
At the time both dogs were registered with council as Staffordshire terriers, he said.
Council officers later determined only one was a Staffordshire terrier and it wasn't involved in the incident. That dog was returned to the owners.
"The dog involved in the incident has since been declared as a restricted breed dog," Mr Crawley said.
Sunbury police are also investigating the incident.
Police have yet to apply for a destruction order for the dog, as the owner has up to 28 days to appeal against the council's determination of the breed.
(Sunbury Leader - Sept 11, 2012)
