Congratulations to Cavalier King Charles Spaniel Jumping Jack - previously known as Jumbo Jack - who's just been crowned the UK's pet slimming champion for 2012 by animal charity PDSA.

Along with 16 other once-overweight pets, seven-year-old Jack has undergone a six-month diet and fitness regime to shed those unwanted pounds and get back in shape.

At the start of the competition, the podgy pooch tipped the scales at 20.5kg - double his ideal weight. But he's now lost 6.4kg and has trimmed 20cm off his waist. Way to go, Jack! (Ahem. Sorry - we came over all whoopy then.)

Owner Rose Welsh, who adopted the champ back in January, reveals: "When Jack first came to us, he was morbidly obese and could barely walk. I couldn't bear to see him in such a sad state, so I took him to the vet to talk about a diet and fitness plan.

"Today he is a different dog and we call him Jumping Jack instead of Jumbo Jack, as he jumps every time he barks now. He's fit, healthy and happy - everything a pet should be."

In total, all the animals taking part lost a very impressive 86kg - or 13st 7lbs, as we prefer to call it. That's roughly equivalent to 28 Yorkshire Terriers or a female giant panda, fact fans!

And if you want to see more of the PDSA's heart-warming success stories, just take a look at our slideshow...

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  • All images PDSA/Rex Features