MADISON (LEE) -- Holly Dieckman-Radloff's beloved basset hound, 10-year-old Zoey, is fat.

She tips the scale at up to 85 pounds, although her owner knows she should weigh about 55.

"She's kind of a steroid baby. She was put on prednisone because of allergies, and it increased her appetite. That kind of started it, that and her owner liking to give a little extra, because I felt I was depriving her," said Dieckman-Radloff, 46, who has owned Zoey since puppyhood.

"It's mostly my fault . . . I suppose I could cut back, but she would be hungry," she said. "She'll go to the refrigerator and slap it with her paw, or go to the cupboards, or sit here and do a little growl thing."

Just as Americans are getting fatter, so are their pets. According to the National Academy of Sciences, one out of every four dogs and cats in the Western world is now obese. Like obese humans, they run a higher risk of developing diabetes, heart disease, and joint and hip difficulties.

The academy estimate may be conservative, says a local veterinary expert.

"Some journals are saying that 40 percent of dogs and cats are obese," said Dr. Sandi Sawchuk, a clinical instructor at the UW-Madison School of Veterinary Medicine, who specializes in small pets. "It's the same thing that's happening to us (humans). There's a high correlation of obesity in pets to obesity in people," she said. "If you're exercising and taking your dog with you, you're both going to benefit from it."

Overweight dogs can suffer joint injuries, arthritis, extra strain on the heart, and tire more easily, Sawchuk said. Overweight cats commonly get diabetes, can get arthritis, and are unable to groom themselves. Both have higher rates of cancer if overweight.

A veterinarian for 26 years, Sawchuk said she sees fat pets much more often now than she did in the early years of her practice. There are many reasons for the change, not least of which is that pet owners often equate food with love. "We're the ones that do it to them. We're killing them with love," she said.

Dieckman-Radloff, whose Zoey is one of Sawchuk's patients, can attest to that. "She's my baby, so she gets the world," she said. "She gets anything she wants."

She feeds Zoey three cups of dry food daily, with carrots or green beans as treats. She tried to put Zoey on a 1 1/2-cup-a-day diet once, "and it just seemed like she's starving," Dieckman-Radloff said.

Sawchuk said one problem is that pet owners today are presented with a dazzling array of premium pet foods, "making it much easier for pets to have high-octane food. And treats are readily available now with a lot more treating going on, of very palatable, high-fat foods."

And dogs and cats, once working animals, have become indoor animals with much less exercise than years ago, Sawchuk said. "Having a fenced back yard and putting the dog out there is not exercise. Go out there with a Frisbee or a ball."

"The number one thing that will convince people is that obese pets don't live as long. Pets kept lean to normal live 15 percent longer," she said.

Kristin Repyak, 27, adopted Smokey Jo, a tortoise-shell, tiger mix cat in August. Smokey Jo, 5, weighed in at 18 pounds, 10 ounces. "She was a big girl. Enormous. She was one of the laziest cats you've ever met," Repyak said.

Repyak immediately got the cat in to see Sawchuk, who prescribed a high-protein, low-fat, low-carbohydrate diet available through the clinic. "She started with 1/3 cup morning and evening and we have six food dishes around the house and that's made her work a little bit for her food. It's how she gets her exercise," Repyak said.

When Smokey Jo didn't lose much, "we bumped her down to 1/4 cup morning and night, and she's down to 15 pounds, four ounces. We're very happy with that, but she's definitely hungry at feeding time."

Repyak said Smokey Jo seems happier. "When I first got her, she just laid around. But now she chases her tail. She has a bunch of toys she plays with and she runs around our condo. She'll, like, zoom up and down the stairs. She still looks really big, though."

Tips for keeping your pet healthy

Pets that are lean can live up to 15 percent longer, experts say. Here are tips to help you determine if your cat or dog is too fat:

If you can't feel a dog's ribs, it probably is overweight. Fat deposits on the back and base of the tail, and lack of a discernible waist behind the ribs when viewed from above are other clues a dog is eating too much.

If a cat looks overweight, it is. Heavy fat deposits on the back, bace, and limbs, or a rounded abdomen, are signs of obesity. Ideally, a cat shows a moderate waistline behind the ribs and has a thin covering of fat over the ribs and abdomen.

To help a dog lose weight, feed it smaller amounts of food on its regular feeding schedule, and make sure it is not being fed table scraps. Owners may also choose a low-calorie "diet" dog food or food high in fiber, which may help the dog feel full with fewer calories. Putting less of the same food in a cat's bowl each day will help a fat cat lose weight.

Source: National Academy of Sciences dietary guidelines for cats and dogs.