With pet obesity on the rise in the U.S. and the U.K., one British pet charity is tackling the issue head on by launching a "Biggest Loser"-style contest for some of the country's most overweight pets.

Dubbed "The Pet Fit Club" and organized by the People's Dispensary for Sick Animals (PDSA), the contest's overweight entrants include 11 dogs, five cats and two round rabbits, according to the press release.

The winning prize for the animal that loses the most weight is a year's worth of pet food and a pet-friendly holiday at a Four Seasons hotel.

In Britain, overfeeding a pet to the point of obesity qualifies as animal cruelty. In 2009, the BBC reported on a pet owner who was fined $1,857 for letting his labrador's weight creep up to 154 pounds.

With more than half of U.S. adult dogs and cats overweight, pet obesity is responsible for a number of health issues including diabetes, kidney failure, and cancer.

In 2010, U.S. pet owners using one particular insurance company paid vets $25 million to treat obesity-related conditions such as asthma, according to the Wall Street Journal.

For those concerned about their obese pets, experts say it's important to work with a veterinarian to tackle the problem.

The Association for Pet Obesity Prevention recommends a high protein, low carbohydrate diet along with plenty of exercise -- 20 to 30 minutes for dogs and 5 to 15 minutes for cats.

Pet owners can also calculate pet food calories and use a weight translator by visiting www.petobesityprevention.com.

Take a look at some of PDSA's big animals that will aim to lose weight in the new contest:

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  • Fifi is 107% overweight

    Fat cat Fifi Bottomley (8), was found nearly starved to death as a kitten before being taken in by her current owner. Her difficult start in life left her with a tendency to gorge herself at any opportunity. The greedy feline would steal food from other cats, even directly from people's plate's, and despite all attempts to help her, she continued to pile on the pounds.

  • Mini Moo is 94% overweight

    Mega moggy Mini Moo, from Basildon, is undergoing a complete diet overhaul thanks to the vets and nurses at Basildon PDSA PetAid hospital. Mini Moo will eat anything she can get her paws on, from Wotsits to cheese and even butter! And she regularly steals the other cats' food, making it difficult for Sharon to judge just how much food the colossal cat is putting away!

  • Bailey is 80% overweight

    Sweet treats and extra portions have been the dietary downfall of Bailey, a rather round Border Collie from Wishaw in Glasgow.

  • Billy is 93% overweight

    Black-and- white tom cat Billie (10) was nominated for the fat fighting competition by his retired owners. Billie loves his food and always had a bigger and unhealthier appetite than his housemate Bobby, who recently passed away. Devouring his own meals he also had no problem helping himself from Bobby's bowl too!

  • Billy is 34% overweight

    Billy, a cuddly Cocker spaniel with a passion for food, food and more food, has been selected to slim down and shape-up with help from staff at the PDSA PetAid hospital in East Glasgow. Billy started piling on the pounds about two years ago and developed a problem climbing the stairs. He was getting very exhausted after a walk so his owners cut down his extra portions and treats right away but the weight stayed on

  • Ottis is 41% overweight

    Ottis, an overweight Cavalier King Charles Spaniel from Edinburgh, who eats everything in sight and has even been known to steal food from the bin.

  • Bobby is 49% overweight

    Flabby rabbit Bobby, from Richmond in North Yorkshire. Bobby has gradually piled on the pounds over the last few years until her owner noticed that her large dewlap (the fold under her chin) was making it difficult for Bobby to groom herself properly.

  • Casper is 91% overweight

    Sneaky food thief Casper the cat, from Stockbridge, Edinburgh. Over the years, the pounds piled on, despite the owner trying her hardest to help him lose weight.

  • Jack is 105% overweight

    Cavalier King Charles Spaniel Jack (7) was rehomed earlier this year by his current owner, and is undergoing a complete life transformation

  • Dexter is 90% overweight

    Podgy pooch Dexter, from Cheshire, weight problems began after he was neutered and he soon piled on the pounds.

  • Maverick is 85% overweight

    Mighty cat Maverick, from Leith, Edinburgh, is the biggest cat ever seen by PDSA Vets in Edinburgh.

  • Alfie is 22% overweight

    Big Alfie, from Strood, Kent, the weight problems began after he started limping at the age of three. He suffers from both arthritis and hip dysplasia and the excess weight he is carrying is adding to his misery

  • Merlin is 111% overweight

    Merlin's weight problems began after he was neutered and his extra bulk is causing him mobility problems and he has developed arthritis.

  • Molly is 64% overweight

    Rotund Rottweiler Molly, from Barnsley, the weight problems started when the pair began serving Molly their food leftovers and visitors couldn't resist giving her a treat from the jar when they popped round.

  • Skippy is 45% overweight

    Spoilt Springer Spaniel Skippy weight problems began after he was neutered and his greedy appetite does not help matters.

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