Dogs who hound their owners at the dinner table have something worse than bad manners. Chances are excellent they’re pudgy around the middle, a hazard of freeloading.

Cats are not exempt from this scenario, although they’re just as likely to make demands while their owners are snacking on the couch.

The point is that animals who nosh on people food are being overindulged, and the results are usually obesity, says Thomas Cliffe, a veterinarian at Graham Road Animal Hospital in Stow, Ohio.

Obesity is frightening because it abbreviates an animal’s already short life span, he says. It makes the ravages of arthritis more painful and can pave the way for the onset of other diseases.

Cliffe is not one to paint the picture black. “I’m not going to talk about constipation,” he says, chuckling. But others do. Purina, the dog food manufacturer, reports that obesity is the No. 1 nutritional disorder among dogs, with 25 percent of them overweight. That puts them at risk for cardiac and pulmonary system trouble, and yes, constipation, which can lead to other problems.

Testing an animal’s fatness

Cliffe stretches out a handsome tabby cat named Tigger, whose round tummy is proof of the pudding. It’s almost invisible when the cat’s on all fours, except his girth is a little too relaxed. If you looked at Tigger sideways, there’s a sag in the middle. The sag should be straight across.

The average person probably wouldn’t consider him fat, but 20 percent or more above ideal body weight is all that’s needed to send an animal into a downward spiral.

Owners can determine whether their dogs and cats are too heavy by placing their thumbs on either side of the animal’s spine, and lightly feeling for its ribs with their fingertips. If you can’t feel them with a light touch, the animal is overweight, says Cliffe.

How your creatures got that way is simple. Although some animals may have genetic predispositions to obesity or hormonal disorders (if you’re worried about this, see your vet), the usual culprit is much less sinister: too many calories and too little exercise.

“Take away 10 percent of its food,” Cliffe says firmly. “This is not a crash diet. The weight will come off slower than it goes on.”

To keep your animals from whining, feed them small amounts two or three times a day. If that’s not enough, stretch out the dog or cat food with raw carrots or canned green beans.

“If there’s food in the bowl at the end of the day, you’re feeding them too much,” says Cliffe.

Feeding rituals

Overweight dogs will get maximum mileage out of a high quality, low-fat dog food.

“Low-fat pet foods are OK, even good,” says Cliffe, “but I’ve had dogs that gained weight on them. They will if you give them too much.”

People who have dogs and cats at home should keep the cats’ bowls out of reach of dogs. Cats need more protein than dogs, so their food is meatier, which is why pooches purloin their vittles. But that’s how your chubby mutt got that way. Remember, extra calories are the enemy.

People with two cats not only have double trouble, they also have the colossal challenge of keeping the fat cat out of the skinny cat’s food. Use your ingenuity. Eliminate self-feeding and adopt separate feeding rooms.

Your animals don’t need prescription medicines to lose weight. “I’m not aware of anything that works,” says Cliffe.

Pricey dog foods with gimmicks, such as gravy, are designed to delight the owners, not the dogs. “They aren’t really necessary. If you have a finicky eater, OK,” says Cliffe, “but don’t do anything to stimulate a dog’s appetite.”

Exercise your animals. “Walks are good,” says Cliffe. “A little is better than nothing.”

Cats will sometimes walk on a leash, but this is not practical. If they are bored with their toys, they may chase the beam from a flashlight or laser pointer.

Meanwhile, dogs and their owners, leash in hand, should trudge the road to happy destiny a thinner, healthier physique.

“Don’t give up,” says Cliffe. “Be strong.”