There's nothing quite as cute as unlikely animal friendships, but the relationship between this duck and dog has been rocky in patches - as we can see through their owner's videos.

Occy the labrador and Biggie the duck live in North Carolina, and a clip of them playfighting that was shot when Occy was a puppy three years ago has gone viral.

In the video we see the two animals squaring up to one another, but it's clear who's in charge, as Biggie defends his side of the garden and Occy eventually runs away.

But two years later, a new video shows that the two are now the best of friends. Their owner, Frances Marsh tells NBC News that the two nap together, and eat together - with Biggie eating out of Occy's bowl, thinking he's a dog too. They may still playfight, but they are inseparable.

Frances owns a waterside surf shop, and the two animals attract a lot of attention from passers-by because of their unusual friendship. She says "I'm so used to it I don't realise it's odd, but apparently it is."

We expect they'll be gaining many more fans after their cute friendship has been discovered by the world at large.