At New York's famous Tavern on the Green restaurant, Thunder padded up to the scale. His competition: a miniature pinscher, a beagle, an English Lab and a Chesapeake Bay retriever.

Starting off at 178.8 pounds, the question was, would Thunder be the biggest loser in the canine slim-down competition?

Thunder was always mighty big, but when his owner, Linda Leigh Sacco got busy with two jobs, he became mighty fat.

People know that childhood and adult obesity pose health and social problems. But on animals, well, come on, rub that soft belly!

Except that it's not so cute anymore. With 40 percent of animals over the age of 4 regarded as overweight, veterinarians say they are seeing more diabetes, joint problems and other health issues similar to those of their heavy humans.

Vets say pet fat is not totally the fault of people. More animals are spayed and neutered, slowing metabolism and increasing obesity. Animals tend to stay indoors more, particularly in urban areas. Apartments may be safer, but cats burn more calories climbing trees than couches.

Even people who motivate human clients to climb mountains and drop pounds melt in the face of, well, that face.

Jillian Michaels, the tough personal trainer who bullied contestants on the weight-loss show “The Biggest Loser,” was a complete softie when it came to her Chihuahua, Baxter.

“I just thought it was cute and he's a dog, who cares?” she says.

There were meatballs. Scraps. Accidental treats, like the entire box of hard candy her friend left on the kitchen table. Suddenly, he was 12 pounds.

When her vet told Michaels that her dog could live an extra five years if he shed some weight, the trainer got motivated.

Now instead of meatballs, he gets Science Diet treats.0

Michaels was one of the judges at the recent National PetFit Challenge, sponsored by Hill's Pet Nutrition, Inc. With the Tavern on the Green's normally tourist-filled hallway covered in cat litter boxes, and a terrace available for canine relief, Baxter's final weigh-in was a success – down to 8.6 pounds.

Thunder also proved to be an excellent example, dropping 44.4 pounds to an athletic 134.4 with the help of daily walks and low-carb, high-fiber pet food.

Alas, he wasn't the biggest loser; Milo, the miniature pinscher, stole the crown after dropping from 22.8 pounds to 10.6.

© 2006, The Philadelphia Inquirer.

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