Maxin Bennett's injuries were so severe he was flown to Christchurch Hospital. Photo / Supplied
Trainor didn't wait for an ambulance, loading her son into a car and driving to Hawke's Bay Hospital in Hastings.
Trainor says she was told at the hospital that Maxin's wounds were the most severe dog bites they had seen.
The pair were then transferred by emergency flight to Christchurch Hospital for surgery.
Trainor told the Herald that effect of the attack on her family has been severe.
"My dad still breaks down about the state of my son when he picked him up. He said he can't get the image out of his head," Trainor said, revealing that she also struggles with the physical toll it has taken on her son.
A recent photo shows how Maxin's wounds are healing. Photo / Supplied
The family have two staffordshire terriers and Maxin is still comfortable with them, but has taken to smacking them since he saw his scars.
Trainor said he now shrinks away from strange dogs.
"He gets scared and cuddles into my leg," she said.
Trainor initially believed the dog that bit her son was destroyed after the attack, but learned two months later that it was still alive.
She then lodged a complaint with the Hastings District Council.
Hastings District Council regulatory solutions manager John Payne told the Herald that the council's animal control team didn't hear about the attack until May 23.
He says that, when asked about the delay, the complainant said they understood the dog would be put down by its owner, but that didn't happen.
"Council has been attempting to investigate the matter, but no formal statement has been provided yet, and an investigation is still pending.
A family photo of Maxin Bennett taken in the month before the attack. Photo / Supplied
"Council did seize two dogs from the owner's property on June 10 but had no grounds to hold the dogs and they were released on June 11 on strict conditions," he said.