HE'S the underdog with the overbite who has been described as the world's ugliest dog.

And now Tuna the 'Chiweenie', who has 1.7 million Instagram followers, is set to visit Blackwell's in Oxford for the store's first ever dog signing.

Tuna's owner, Courtney Dasher, said the duo had worked very hard on autobiography Tuna Melts My Heart and were looking forward to presenting it to the people of Oxford on Thursday.

Oxford Mail:

The 34-year-old from Los Angeles said: "Oxford is actually the only stop on my tour of the UK where I'm extending our time by a few hours.

"I want to be able to visit the University, have a nice walk around and eat some of the great food here because it sounds like an amazing city.

"It will be nice for the people in Oxford to have the opportunity to grab a copy of the book and even get a photo next to Tuna."

Tuna, a Chihuahua/Dachshund cross, has gained a massive following on social media since starting out life as a rescue dog with fans including Reese Witherspoon, Lady Gaga and Hilary Duff.

And the events manager for Blackwell's Bookshop, James Orton, said he was anticipating a large group of fans to attend the signing for the book, which gives a photographic account of five-year-old Tuna's life.

Oxford Mail:

He said: "I know that Tuna's signing in Edinburgh attracted about 400 people to the store, which is very exciting, and we're hoping it'll be similar here.

"Obviously, as Tuna is a dog, he won't be actually signing the book but we will have stamp – or a pawdograph – with an imprint of his paw which will be available to every single person who buys a copy of the book in store.

"It's our first ever dog signing event so we're all really looking forward to welcoming people in for a really fun evening."

The event will be running from 5pm to 7pm at Blackwell's store in Broad Street.

No tickets are necessary but copies of Tuna Melts My Heart will need to be bought, which costs £7.99, in order to meet Tuna.

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