Fearsome hound is bred by U.S. firm

His name is Hulk. Well, look at him - what else would you call him?

Weighing twelve and a half stone (175 lbs), he is believed to be the world's largest pit bull. And because he is only 17-months-old, he hasn't stopped growing yet.

Proud owners Marlon and Lisa Grennan, from New Hampshire, say their monster pet is 100 per cent trusted with their three-year-old son, Jordan, despite the breed's fierce reputation and even let him ride the animal like a horse.

Indeed, photographs show the toddler happily riding on the canine's back, grabbing the collar just behind its 28-inch wide head.

While pit bulls are branded 'dangerous' with breeding bans enforced in the UK, Mr Grennan claims they are actually very caring and fit for the family.

Scroll down for video

Impossible to miss: The Grennan's dog is almost three-times bigger than a normal American pit bull terrier

Give us a hug: Hulk is just as tall as his handler Frances Cummings

All aboard! Proud owners of the world's biggest pit bull dog have told how their three-year-old child rides the 175lb pooch like a horse

'These dogs are very balanced and gentle - they are nanny dogs,' he said.

'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.'

However, Mr Grennan acknowledges that a dog the size of the Hulk 'could kill someone if it was in the wrong situation at the wrong time' and 'snap an arm like a toothpick.'

The Grennan's dog is almost three-times bigger than a normal American pit bull terrier.

He is also still a puppy meaning he could grow even bigger.

Each day he is fed a protein-rich diet consisting of supplements and 4lbs of ground beef.

The Grennans believe the bigger the dog, the better.

Giddy up: Marlon and Lisa Grennan, from New Hampshire, say their monster pet 'the Hulk’ is 100 per cent trusted with their son, Jordan, despite the breed's fierce reputation

Open wide: Hulk showcases his big teeth as he's taken for a walk

Dinner is served: Each day he is fed a protein-rich diet consisting of supplements and 4lbs of ground beef

Shall we dance? Hulk with Mrs Grennan at home on February 22, 2015 in New Hampshire

Together they run Dark Dynasty K9s, which specialists in breeding some of the world's most fearsome guard dogs.

Marlon, a former boxer, formed the company ten 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.

These include more than more than a dozen highly trained pit bulls - and a single chihuahua.

And while he admits his dogs are trained for aggression and power, he says the criticism is usually from people who lives in safer environments with no need for protection.

He added: 'It’s very, very, important what I’m doing.

'I live in New Hampshire where there’s no crime and I don’t have to worry about that kind of stuff.

'But I’ve got clients in Grenada and parts of Africa where there is. I’ve got clients in terrible, terrible places. They don’t live in Candyland, they live in fear.

'And why should somebody else live in fear if they don’t have to. So that’s my job, to try to alleviate somebody else’s fear by giving them a family dog too.'

Speaking out: While pit bulls are branded 'dangerous' with breeding bans enforced in the UK, Mr Grennan claims they are actually very caring and fit for the family

Ultimate protection: The Grennans believe the bigger the dog, the better

Going for walkies: Together they run Dark Dynasty K9s, which specialists in breeding some of the world's most fearsome guard dogs