The fuzzy grey animal has a dog’s snout and tongue – but also appears to have pointy ears like a cat.
His adorable appearance has enchanted and confused many online, who can’t decide what species of animal he is.
More than 40,000 people have liked Dúi’s official Facebook fan page just days after it was created, and thousands of Reddit users have admired him after photos were posted to the website.
They speculated he may be a cross between a corgi and a Vietnamese breed called Hmong, while others suggested he could be a corgi mixed with a British shorthair cat.
“So like is it a cat, dog, or some new kind of fox that we will keep seeing on the internet… but nobody knows how to get one?” one Reddit user pondered.
Another joked: “Do you want a cat or a dog? YES.”
His owners have finally answered the speculation: Dúi is actually a mix of a native Vietnamese dog breed and a short-legged dog breed known as Dingo.
He’s 10 weeks old and lives with Hai Anh and Tuan in Hanoi.
Tuan says the dog “might have a gene mutation” that accounts for his unusual but endearing appearance.
“I bought him in a mountain province in Vietnam,” he told Metro .
“He is a happy and sweet pup, he loves to play with other dogs, even big dogs and so sweet with humans.
“It’s been only five days since we created Dúi’s fan page and it now has more than 40,000 likes.
“The dog now has loads of fans both in Vietnam and around the world.”
Translated to English, Dúi means “bamboo rat”, but the adorable puppy seems far from pest-like.