Angus Martig, four, was mauled by his neighbour’s American Bulldog in Quakers Hill on Sunday about 1pm.
Riverstone Police Inspector Al John said Angus was talking to his neighbour on the footpath when he was attacked.
The dog, named Keely, latched onto Angus’s neck and shoulder. His mother, Gillian, and the dog’s owner, Sarah Clinch, ripped Angus from Keely’s hold.
NSW Ambulance Inspector Jennine Kiely said the pair’s intervention “saved the boy’s life”.
The two women also suffered bite marks.
“Seems like they were relatively lucky,” Insp Kiely said.
The dog has since been seized and it’s likely he’ll be put down.
However, neighbours said the attack doesn’t come as a surprise and the dog has a history of being aggressive.
Concerned local mum Jessica Farrell said she has four children and the dog attacking someone was “an accident waiting to happen”.
She added passing the house where the dog lives is the only way out of the street.
“I’m petrified every time I take them to the park. We have to be super quiet when we walk past the house,” Ms Farrell said.
Angus was taken to The Children’s Hospital in Westmead for treatment.