Photos: This super sized pit bull has to be the biggest I've seen

UK, breeders Marlon and Lisa Grennan say their monster dog named "Hulk" is 100 per cent trusted with their young son.

The couple's business, Dark Dynasty K9s, supplies protection dogs to high-profile celebrities, billionaires and wealthy professionals - as well as law enforcement around the world.

Mr Grennan, 28, said: "A dog the size of the Hulk could kill someone if it was in the wrong situation at the wrong time. The power of this dog is unrivalled. If he bit down on someone's arm with full power it would snap like a toothpick. But he doesn't have that kind of mentality. These dogs are very balanced and gentle - they are nanny dogs."

Mrs Grennan, 24, who is herself dwarfed by 17-month-old Hulk, said the American pit bull terrier breed is misunderstood.

"I have no concerns about any of the dogs around my son," she said. "They are amazing family dogs. People say these dogs randomly flip out, but that just doesn't happen.

"They go through enormous amounts of training and are more used to going up against multiple grown men and hearing loud noises. So the little things a kid might do to startle a regular dog isn't going to phase ours at all."

Mr Grennan is a former boxer and formed the company 10 years ago with just two dogs after suffering a hand injury that ended his career.

They now own many dogs that live in the house with the family on a 150-acre ranch in New Hampshire, USA.

Telegraph