She's the dog who won't give up and he's the toddler who shuns human contact.

But, as this video posted on YouTube shows, persistence and patience win in the end and an unlikely friendship is formed.

The gentle labrador is Himalaya. She managed to coax Hernan, a shy boy from Buenos Aires with Down Syndrome, into playing with her.

Such is the bond the two strike, Hernan ends up giving Himalaya a hug.

Hernan's mother, Ana Marta Vegas, posted the video last year but in the last couple of days the heart-warming clip went viral.

She wrote on her YouTube account that son usually shies away from contact: "Hernan, is a bit withdrawn and flees from physical contact. He does not like be touched, but Himalaya insisted so patiently, and she was so soft that's why it is so moving, she is left to do anything."