By John Balson @JJBalson
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Videographer / director: Ruaridh Connellan
Producer: John Balson, Nick Johnson
Editor: Joshua Douglas
Marlon and Lisa Grennan will even let world-famous Hulk lick and watch over their tiny boy, Jackson.
But it’s not the first time the couple have done this, as their eldest son, Jordan, grew up with Hulk and other American pitbull terriers on their property in New Hampshire, USA.
Lisa, 25, said: “I have no worries with Hulk being around the baby. It’s not a big deal.
“When we brought Jackson home Hulk was all over him. He was watching me while I cared for him and he would go and check on him when he would cry.
“He is the perfect protector and babysitter.
"He followed me around everywhere. We couldn’t ask for a better dog. He really does love him and you can see it in his eyes.”
Marlon’s company Dark Dynasty K9s specialise in training elite protection dogs for the police, celebrities and billionaire clients around the world.
They hit fame in 2015 when videos featuring Hulk and their other dogs went viral - clocking up more than 100 million views on YouTube alone.
Many of the videos show Hulk working as a protection dog, often practising bite work on Marlon, his trainers and occasionally this young son Jordan too.
Despite Hulk’s bite being powerful enough to ‘snap someone’s arm like a toothpick’ they had no fear introducing newborn Jackson to the pack.
Lisa added: “When you see videos of Hulk working and doing bite work that’s just his other side.
“He’s a working dog, a protection dog and a dog that is able to do that has to be very balanced and stable.
“His job is to protect the family, so he has to be a good family dog too.
“It is all monitored. I would never put Jackson on the floor and leave him with the dogs.
"I do trust Hulk. They are very balanced and stable dogs and they know he is a baby - and just like their own babies they know how to be gentle.
“The main criticism that we get is 'how do you let your dog lick your baby?', which to me is silly.
“I let the dog lick me and I don’t think it is dirty and it’s not a big deal - but I do monitor that too and won’t let Jackson get smothered."
Hulk weighs 24 times greater than the baby but dad Marlon, 28, is confident his training and leadership will keep everyone safe.
“Even when Jackson was a mere few hours old we were ready to take him home to meet the pack. I wasn’t worried at all.
“When you’re the leader of that pack and there’s structure, rules, boundaries, limits and leadership, then there’s nothing to be worried about. I’m always in control.”
Keep up with the Dark Dynasty K9s family on the show Dog Dynasty, featured on the Barcroft Animals YouTube channel.