THE country's biggest pets are once again being given the chance to take part in a fat-fighting contest.

And the owner of last year's winner - former bulging bulldog Daisy from Middlesbrough - says the difference is amazing after she succeeded in shedding more than a quarter of her bodyweight.

Daisy was crowned pet slimmer of the year after starting the competition weighing in at 28.3kg but lost around 8kg with the help of the veterinary charity PDSA's annual Pet Fit Club.

Owner Gillian Turrell said: "The difference in Daisy is amazing. Losing the weight has really improved her mobility. Before she struggled to climb the stairs - now she sprints up them.

"I'm so grateful to the vet staff at Middlesbrough PDSA Pet Hospital for their help and guidance, and for how they've helped to transform Daisy's life. I'd encourage any pet owner worried about their pet's weight to enter Pet Fit Club."

Early entrants to the competition include a cocker spaniel called Millie, who is nearly twice the size she should be, and black cat Boycus, who tips the scales at 10kg - double the size of your average moggie.

Millie's owner Jacqueline Maguire, 75, from Romford, said: "I do give in to her begging far too often. I have four rescue cats and when I feed them she's hovering around and grabs any food she can.

"I have to shut her in another room and feed them on the table. Even then, if I turn my back for a moment, she'll be straight in. She'll steal and eat all the cats' food given the slightest chance."

Sam Denning, from Sutton Coldfield, owner of rescue cat Boycus, said: "We've had Boycus since he was a kitten and he's seven years old now. The weight gain has happened in the past two years, despite our efforts.

"We've tried everything - we've built feeding stations with cat carriers that are too small for him to try and stop him stealing our other cats' food, but he always finds a way to break in."

Obesity isn't confined to just cats and dogs - and even affects rodents such as Spider the rat, who at 900g is almost double the size of an average rat.

Owner Eryl Burton, from Swansea, said: "We called him Spider because when we first put him in his cage he ran straight to the top and hung in the corner, like a spider would. Now he has just ballooned and gets stuck in his igloo. We think of him as a gentle giant as he's very placid and is only dominant when it comes to food."

Nicola Martin, PDSA head of pet health and welfare, added: "PDSA's research has shown that pet obesity is a growing problem and that too many people are continuing to feed their pets inappropriate foods including takeaways, cake, cheese and chips and sadly many pets aren't getting enough exercise.

"Pet obesity is entirely preventable and we're trying to help owners understand that while their pets may beg for food, and giving a treat is seen as a way of showing affection, ultimately it could be killing them with kindness.

"Over the past decade, Pet Fit Club has transformed the lives of some of the UK's most obese pets, having helped nearly 100 animals shed over 60 stone, so we are welcoming entries again and offering our expertise."

Pet Fit Club participants will take part in a tailored diet and exercise programme, overseen by vets and nurses over a six-month period. Owners can enter their pets at www.petfitclub.org.uk.