He is a fully grown Rottweiler. She is a tiny wolf pup.
But that hasn't stopped 18-month-old,150lb dog Ulrok and and eight-week-old cub Beldaran becoming best of friends
They sleep together, frolic in the sun and even howl at the moon in unison - and their unlikely union brings a smile to the face of everyone who sees them.
Beldaran, who weighs just five pounds, was adopted by the Rottweiler when she was just four days old at the Kisma Preserve in Mt Desert, Maine, USA, after she was rejected by her parents.
Once Beldaran is full size and can fend for herself, Heather plans to gradually introduce her to a group of adult wolves at the park
Barking mad: Rottweiler Ulrok has become so close to wolf cub Beldarin they even howl in unison
Since then the unlikely pair have been inseparable in everything they do.
Both are rescue animals and spend all of their time together at the reserve where they are cared for at the centre's sanctuary. The organisation takes in creatures of all breeds and all sizes.
Preserve director Heather Grierson, 49, said: 'It's a true love story that has touched the hearts of everyone who visits the preserve.
'You just can't be in a bad mood when these two are around. It's impossible to look at them and not feel good.'
Beldaran is lovingly described as a 'little accident' by the 12 staff at the sanctuary - who didn't know she was due and believed her rescued parents Gandalf, one, and Kahlani, two, were too young to have babies.
Both are rescue animals and spend all of their time together at the reserve
Both parents were handed in to the sanctuary when they were young.
It is thought they had been snatched from the wild for the purpose of breeding them with dogs to make hybrids - a fad in America.
'It causes many problems,' said Heather.
'It's purely for fashion and people don't realise the difficulties of caring for these wild breeds.
'Then they either dump them or hand them over to us.
'It was a massive shock when Kahlani gave birth,' she added.
'We didn't even know Gandalf had it in him and suddenly we had a little wolf pup on our hands.'
Sadly, because of her young age, Kahlani's maternal instincts failed to kick in and she ignored the new arrival.
Heather said: 'We started to get really worried because Gandalf didn't have a clue what to do and we were really concerned he might hurt Beldaran.'
Tough love: the wolf's new 'father' shows the youngster who is boss
In an effort to get the pup some maternal care, Heather and her team placed Beldaran with another canine at the centre - Yorkshire Terrier Mia - who had just finished raising her own litter and was still lactating.
But the Yorkie wasn't interested either and made every effort to avoid the pup that was being pushed on her. 'That's when Ulrok stepped up,' said Heather.
'Ever since Beldaran's arrival he had been trying to get involved in everything. He would clean her and when she was making her puppy whimpering he would bound over to investigate.
'He had such a massive interest in her that we decided he would be the best option and we could bottle feed the wolf. It worked out brilliantly.'
Now Ulrok - a rescue dog whose previous owners imported him from Europe and gave him up when they couldn't cope - and his new love eat, drink, play and sleep together.
The duo have also become a huge attraction at the reserve.
Once Beldaran is full size and can fend for herself, Heather plans to gradually introduce her to a group of adult wolves at the park to make sure she stays all wolf and is not alienated from her own species.
'At this stage it has all been about giving her a paternal figure and Ulrok accepted the role gladly.
'At 18 months he is still a puppy in his head and he also needed a companion to play with.
'It was a perfect match. Dogs and wolves are very similar biologically and they both need strong social ties when they develop.
'We'll eventually move Beldaran in with the other wolves in phases but I'm sure her bond with Ulrok will always be there. After all this time together they will never forget each other.'
Barking but true: The touching bond between a Rottweiler and a wolf cub | Mail Online