His mother, Katarina Kopa, who lives elsewhere in Otahuhu with her own mother, Ngawai Henare-Hohepa, said her boy, whom she calls "Little Man", had had one operation and more were expected.
Ms Henare-Hohepa said Shepherd's father, Orlando, had described the attack to her.
"He was cooking dinner. Little Man was playing out the back. He just heard him screaming. The dog was barking a lot. He went running out and the dog had his [Shepherd's] head in his mouth. The dog was thrashing him around in his mouth. All the injuries are around his head and face.
"He was being dragged around.
"He [Orlando] grabbed a shovel and started smashing the dog. The dog ran and attacked him. He managed to get the dog away from his son and he picked his son up and rang the ambulance straight away."
Ms Kopa, 23, who has three other children, said after seeing her boy in hospital yesterday: "He's all right. He's way better than yesterday. He's awake and he can talk a little bit.
"The first thing he said to me was, 'Mummy, the dog bit me'.
"A plastic surgeon came to talk to me. They have already done some stitches. They said there's a serious one [wound] at the back of his head."
One eye had been injured and a nerve damaged.
Ms Kopa said she was "mad and sad" about the attack but "I'm just glad that he is alive".
She said people should not be permitted to have violent dogs.
People at the Beatty St house yesterday said the boy's family were not there. The large, brown dog is reportedly a pitbull.
An Auckland Council spokeswoman said Animal Control Services had taken the dog and was investigating the incident. A decision had not been made on whether it would be put down.
A Beatty St neighbour said she noticed the "quite massive" dog a fortnight ago and stopped her 6-year-old son from playing in their own backyard because the wire-netting fence was not secure.
Minister: Review of case needed
Housing New Zealand has a no-dog policy, in which tenants are allowed to keep dogs only in exceptional circumstances, such as sight or hearing dogs.
Housing Minister Nick Smith told Radio New Zealand today the incident was an "awful tragedy" and he wanted a review of the case to see if there was anything more that could have done.
"I'm happy to have a review of the case and see whether there are any lessons Housing New Zealand can learn to make our homes safer from these sorts of dog attack," he said.
The dog had only been at the address for a few weeks, Dr Smith said.
"I'm interested to know whether any Housing New Zealand tenants reported the breach of policy to Housing New Zealand, or to anybody else.
"It's not that Housing New Zealand is responsible, but wherever possible we want to be providing safe-havens for children and not having these sorts of incidents."
Dr Smith said he understood the father had other dogs at the address in February.
"And that's why he was reminded of the policy at that time."
Dr Smith said the no-dog policy was being enforced.
"I can assure that it is being enforced because I get dozens of letters every week from people that are upset with Housing New Zealand," he said.
Tenants who did not get rid of a dog were given notice and required to cease their tenancy. However, that was an extreme step.
Canine casualties
• Around 12,000 people a year seek medical treatment for dog bites.
• July 19 - Caleb Heka, 17, mauled by his pitbull in West Auckland
• July - 5-year-old Greymouth girl had surgery after a dog bit a chunk out of her face.
• March - Sakurako Uehara, aged 7, was mauled at Murupara by four Staffordshire bull terrier-cross dogs. She faces years of reconstructive surgery to repair extensive wounds from bites to her face, limbs and almost every part of her body.
