Wilton woman Rosemary O'Reilly died in hospital after she was attacked by her own dog last Thursday.
Ms O'Reilly, 72, suffered significant bite wounds and lacerations to her arms, legs and body when she was attacked by the large Staffordshire terrier-Rhodesian ridgeback cross at her Hornby Street home.
Her husband Derek, 74, was also injured.
Emergency services were called to their home about 1.30pm last Thursday.
The couple were treated by paramedics at the scene and rushed via ambulance to Liverpool Hospital. The woman's condition deteriorated and she died later that day.
The dog was seized by Wollondilly Council rangers.
A decision on whether the dog will be euthanised has yet to be made.
A council spokeswoman said the council was following the regulatory process for "managing a dangerous dog" under the NSW Companion Animals Act (1998).
The spokeswoman said the impounded dog was registered and council had no record of any previous reports about the dog's behaviour.
"The fatal dog attack that took place at Wilton yesterday is extremely upsetting to us and our community," she said.
"Or thoughts are with the family and all of the first responders that had to manage this very distressing incident."
A report was prepared for the information of the state Coroner.