ALBANY, N.Y. — You’ve probably heard that old saw about how pets and their owners tend to look alike.

Well, turns out we’ve got more in common with our furry companions than matching mugs: According to a study in the Journal of Veterinary Internal Medicine, as many as 40 percent of dogs and cats may be obese — weighing in at 20 percent or more above what’s considered the ideal body weight for their breed and age.

While your fat cat may seem happy, he may be facing some of the same health problems that plague overweight humans: diabetes, decreased stamina and immune function, dermatological problems, as well as musculoskeletal and orthopedic problems, according to veterinarians.

The causes for pet-weight problems: Lack of exercise, poor diet and over-eating, genetic predisposition, and thyroid or pituitary problems.

Sound familiar?

Your vet knows best based on your pet’s history and breed, when it comes to determining whether your pet’s weight is — or may become — an issue.

Some dog breeds, for example beagles and basset hounds, are genetically predisposed to weight issues; studies have shown that mixed-breed cats are more prone to weight gain. House cats also have more weight issues than those with outdoor privileges.

Neutering and spaying can affect a pet’s metabolism, and thus weight, as well.

To tell if your pet is (un)pleasantly plump, a simple, visual sizing-up should do the trick.

Is your pet fat?

First thing first:

Vets suggest you:

• Feel for ribs: Place your thumbs on your pet’s backbone and gently run your palms across his rib cage. You should be able to feel his ribs, without exerting much pressure.

• Waist hunt: Check your pet’s profile from multiple angles. From the side, an overweight pet’s belly will be obvious, sometimes pendulous, just south of the rib cage. For long-haired animals, gently feel for paunch; on cats, a tell-tale sign is a wobbly “apron” of belly fat. From above, look to see if the waist dips in below the ribs. No waist? Your pet’s got a weight problem.

• Before dieting: When it comes to putting an overweight pet on a diet, first consult your vet. He or she can determine a goal weight, and help come up with a diet plan.

• Food/exercise balance: However, generally speaking, dogs and cats gain weight for the same reasons we do: They’re eating more calories than they burn. The remedy is the same for them, too: Eat fewer calories, burn more calories.

• Check their diet: Buy low-calorie food (aka “weight-reducing” formulas, with less than 10 percent fat and at least 15 percent fiber), available just about anywhere that sells pet supplies. Feed your pet at set times, and regulate the amount. Don’t leave a bowl of food sitting around 24/7 and stop giving your pet table scraps.

• Weigh your pet regularly: If you can lift the animal yourself, weigh yourself first, then with your pet in your arms. Subtract. For larger pets, weigh-in at your vet’s.

• Exercise your pet more: Increase your walks or play time, if you’ve got a dog. If you’ve got a cat, an animal whose waking day ranges between six and eight hours, shedding pounds through exercise can be tough.

• Try toys: If your cat responds to play — chasing or attacking feathers, pet store gadgets, or even the dot of a laser pointer — spend more time at these activities. Even a “lazy” cat may perk up when inspired by a new toy/pursuit.