In the third serious dog attack in under a week, the little boy was riding down Antill Street in the suburb of Mayfield with his mother and older sister shortly after 6.30pm yesterday when the large dog ran out of an open gate and lunged.
Detective Acting Inspector Jeffrey Little said it was fortunate the child wasn't more seriously injured.
The dog retreated to its property, while the boy was treated by paramedics at the scene before being taken to John Hunter Hospital.
Police have spoken to the boy's mother, who they say is "holding up quite well".
"Everybody is lucky in this circumstance that it hasn’t ended up worse," Detective Little said.
Police and the local council are investigating the attack, and there was "every chance" the dog responsible would be destroyed.
It comes just days after a 12-month-old baby girl Kamillah was mauled to death by a Rottweiler at her grandmother’s house in the central NSW town of Inverell on Saturday.
The girl remains in hospital, while the dog responsible for the attack has been put down.
Detective Little said the spat of attacks should serve as a timely reminder to dog owners and parents alike to be vigilant when children are around unleashed dogs.
"It goes without saying, without telling parents how to do their job, just to be vigilant when they are outside with their kids. There is always a potential when there is a dog which is running loose," he said.
"Children are particularly vulnerable to attacks by dogs by their mere size, and certainly they can suffer serious physical and psychological injuries – and unfortunately, as we’ve seen in recent days, even death."
The Great Dane that attacked the little boy
He also urged anyone with concerns about a potentially dangerous dog to contact their local council.
"Dogs are an animal, and every dog has the potential - large or small - to attack."
In New South Wales, dog owners whose pets are involved in an attack face up to five years' imprisonment and fines of up to $77,000.
(9News - March 6, 2018)