Toddler and dog
A Labrador Retriever tries to play with a toddler.

A heartwarming clip of a dog befriending a young boy with Down's syndrome has sparked controversy over its origin after it went viral online.

The YouTube footage, posted in 2012 under the username Jan Fernandez, shows a small boy sitting on a patio in front of a female Labrador.

As the dog tries to play with the child, he remains hesitant and repeatedly backs away from physical interaction.

But determined to win over his new friend, the dog perseveres by first placing a gentle paw on the little boy's foot before dropping her head in his lap.

The dog can later be seen affectionately putting a paw on the young boy's shoulder, seemingly trying to reassure the child.

The youngster ends up giving the sweet canine what looks like an embrace around the 3:12 mark.

One viewer said: "Can we clone this dog and give her to everybody on earth? Will end wars with her sweetness."

While the clip has touched users from across the world, it has also raised questions about its authenticity.

According to the video description, the little boy is three-year-old Hernán from La Plata, Buenos Aires, who is 'a bit withdrawn and flees from physical contact.'

However, an identical video, also uploaded last year, names the duo as James and Rufus and claims that the footage shows them 'spending time together'.

One confused commenter said: "How could this boy be Harman, when his name is James, playing with his dog Rufus."

Another said: "The names of the boy and dog are Hernan and Himalaya.

"Doesn't seem right for this user to be capitalizing on someone else's video and even using different names."

Down's Syndrome is a genetic condition caused by the presence of all or part of a third copy of chromosome. It is the most common chromosome abnormality in humans.

Those with the disorder typically have a characteristic range of physical features and suffer from some level of learning disability.