KEY POINTS:
The dog sits silently, close to the cage doors, and watches as people file past.
It doesn't move or make a sound until someone gets closer to the cage and then it erupts - barking loudly, and leaping on to its hind legs.
Experienced animal welfare officers have labelled this dog the most aggressive they have ever seen.
They want it destroyed after it mauled a 2-year-old boy on Thursday, leaving him with a broken jaw and serious facial wounds.
The dog's chain still hangs around its neck because officers can't get into the cage while it is so unpredictable.
The injured boy, who is the son of the dog's owners, is in a critical condition in the Starship hospital.
He was attacked at his home in Te Atatu South after he wandered into the area where the dog was chained to its kennel.
Officers from Waitakere City Council's animal control unit who seized the dog were shocked that it bent one of the two strong aluminium catch poles as it tried to evade them.
Animal welfare manager Neil Wells placed the dog at the top of the scale in terms of its aggressiveness and said it was scary to think it had been trained that way.
He said the dog owner had said it had been kept as a guard dog.
"It's a very aggressive dog ... we are being very careful with it," Mr Wells said.
The dog - a red-nosed pitbull - was not naturally aggressive, he said.
It would be held by the council until the police had completed their inquiry.
The dog was not registered but was on a chain when the attack happened.
"Somehow the child has wandered into the area and that's where the attack happened. You should never let any young children access [dogs] without supervision," Mr Wells said.
There was another dog on the property which would be investigated.
The incident was the worst he'd seen in years and the council would seek a court order for the dog to be destroyed if the owner didn't consent.
Mr Wells said that in an earlier case it took 18 months to obtain a court order.
Police have spoken to the family but have not taken formal statements. Once that is done they will decide if any charges will be laid.
