'Hulk' is not your average family pet, and is actually a breed of dog that is banned in the UK, but breeders Marlon and Lisa Grennan say he is '100 per cent trusted' with their young son - despite his size and strength.
Marlon, 28, told Barcroft Media: "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."
Despite the lethal potential of 12-stone Hulk and the couple's many other dogs, their three-year-old son Jordan has grown up with them within arm's reach.
And mum Lisa, 24, who is herself dwarfed by 17-month-old Hulk, says the American pit bull terrier breed is misunderstood.
"I have no concerns about any of the dogs around my son. 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."
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.
Marlon, a former boxer, formed the company 10 years ago with just two dogs, after suffering a hand injury which ended his career.
They now own more scores of dogs, many who live in the house with the family on a sprawling 150-acre ranch in New Hampshire, USA.
These include more than more than a dozen highly trained pit bulls - and a single chihuahua.
Many of the pit bulls eat a protein-rich diet of ground beef and protein supplements, in much the same way a bodybuilder would. The Hulk alone eats 4lbs of ground beef each day.
The couple's protection pit bulls are trained to have 'no fear' and their top specialist dogs, including ones named Ace and the General, can even run up the side of fences and walls to reach second-floor windows.
Marlon added: "These dogs are absolutely fearless because they are trained to be one hundred per cent fearless. They feel nothing. They know no defeat. We are constantly going to throw challenges in front of them because creating that fearlessness is what makes a good protection dog."
Marlon and Lisa breed two different type of pit bull. Some like the Hulk, who is expected to become the biggest pit bull in the world, are bred for size.
Whilst the average pit bull male will weigh 35-60lb, the Hulk, at 175lb, is almost three-times bigger than a normal American pit bull terrier.
He is also still a puppy meaning he could grow even bigger.
And their big size and expert training means they can command high prices.
Marlon said: "A dog like Hulk can cost you anywhere from $2500 to $25,000. I have one of his sons who might be sold for $30,000 just based on who he is, what he does and who we are.
"But I would never consider selling Hulk. I've been offered $200,000, $250,000, $500,000. You could throw ten million in front of me and I'd throw it right back at you. The dog is priceless, period."
Marlon says he is frustrated by the way pit bulls are portrayed as overly aggressive breed and hopes to change opinions.
He is so confident, he allows Jordan to ride the Hulk and kiss his monster 28-inch wide head.
He added: "I don't think it's irresponsible for people to have pit bulls and children. They're dogs just like any other dog. No matter what the breed it is, it is hundred per cent how you raise them.
"The main thing with us is the level of care we put into these dogs. We are dogs, we live and breathe this world every single day, so the amount of care that goes into it is like nothing else in the world."
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