The dogs were impounded by the Southland District Council and an investigation is under way.
The partner of the owner of one of the two rottweilers, who asked to remain anonymous, told the New Zealand Herald the "lovely'' dogs were not at fault, alleging Beaumont opened his gate and entered his property before the attack.
His partner owned the female dog, Zara, and the male dog, Frank, belonged to his partner's father.
"I am sorry for what has happened, but we are not bad owners and they are not bad dogs.
"They were protecting their home like all normal dogs would.
"They are lovely dogs and very protective of their home.
"We got the dogs to guard our house and be our forever friends.''
The suggestion that Beaumont, who has autism, had entered the property was rejected by his father Chris.
"Oliver has always been afraid of dogs as he was attacked three years ago by a similar breed of dog.''
"These dogs make noise whenever anyone walks past.
"There's no way Oliver would even go near those dogs, let alone open the gate.''
A video of the attack supplied to Stuff appeared to show the dogs attacking in the gravel road Beaumont was walking on, not in the yard containing the dogs.
His neighbour Annie Burazor, who was first on the scene of the attack and administered first aid before rushing Beaumont to safety after an off-duty police officer drove away the dogs, said the victim would not have provoked the mauling.
"He would not approach the dogs.
"He walks that walk every day multiple times up and down and those dogs are always barking on everyone and everything walking by their house.
"They are not the type of dogs that you would ever want to get up close to.''