VIDEO: This border collie knows more than 1000 words

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This might just be the world's smartest dog.

Her name is Chaser and she has a vocabulary of more 1022 words – she just can't say them.

But she can understand them, and that makes for an interesting game of fetch.

Her owner John Pilley, a retired professor of psychology from Wofford College in South Carolina, trained her to recognise this impressive amount of words using toys.

Each word is associated with a different toy.

So when the pair play their version of fetch, it's more like a word game – as you can see from the video.

The clip, taken from BBC's 2012 series Super Smart Animals, was posted to the BBC Earth YouTube channel yesterday, and has already clocked up close to 15,000 views.

Pilley's research with the cluey border collie culminated in a book Chaser: Unlocking the Genius of the Dog Who Knows a Thousand Words, which explores the potential of animal intelligence.

But Chaser isn't just some kind of lab rat – she's a member of the Pilley family.

Chaser came into his life after Pilley's wife Sally grew tired of his "moping around" in retirement.

"I never dreamed that when I reached the age of 85 that I would be still training dogs," he said in a video about Chaser on his YouTube channel.

"But I confess that I'm possessed. She's always happy, and that makes me happy."