As if the obesity epidemic weren't already a weighty enough issue, it turns out we're not the only ones getting fat and risking our health.fat-cat

Our pets are getting pudgy, too, and they're paying a big price.

Petplan, a pet insurance company based in Philadelphia, says its 2011 claims data show obesity-related illnesses and injuries for cats and dogs are on the rise.

Claims for arthritis more than tripled last year, rising 348 percent from the previous year. Claims for diabetes more than doubled, up 253 percent. Claims for cardiac disease rose 32 percent, while injuries linked to obesity, such as cruciate ligament tears, neared the top of the list of conditions generating the most claims, Petplan said.

All of those conditions can affect any pet, but fat cats and dogs are at higher risk.

What's to blame? The same factors making people fat and boosting human health insurance costs are at work for pets -- too little exercise and too much food.

More than half of the nation's dogs and cats are now overweight, according to a recent study by the Association for Pet Obesity Prevention. Its survey found 55 percent of cats and 53 percent dogs were overweight or obese in 2011.

Dogs and cats haven't caught up to their human counterparts; two-thirds of Americans are overweight or obese.

But the numbers are still grim. Although the overall portion of overweight pets has remained fairly steady in the last few years, more pets are becoming obese -- weighing in at 30 percent or more above normal. Last year, almost 25 percent of cats were classified as obese, compared to 19 percent in 2007. Meanwhile, 21.4 percent of dogs were obese, up from 10 percent in 2007.

What's more, many pet owners remain in denial -- 22 percent of dog owners and 15 percent of cat owners said their pets were normal weight, when the dogs and cats were actually overweight or obese, the study found.

Veterinary bills for obesity-related illnesses can weigh heavily on the family budget. The average cost for veterinary care for diabetes in 2011 was more than $900 per incident, with some insurance claims ballooning to $5,700, according to Petplan. Cruciate tears averaged $2,000, but some claims totaled more than $6,000. Arthritis claims averaged $2,000 per incident, with the highest per-policy cost at $9,600.

The best medicine for overweight pets is careful feeding and regular exercise.

Petplan offers the following tips:

· Cut out table scraps and dump fatty treats for low-calorie whole foods, such as baby carrots and string beans.

· Consider switching to twice-daily feedings instead of letting pets graze throughout the day.

· Think portion control. Ask your vet how much you should feed your pet.

· For sedentary pets, start with easy, short walks and build up exercise gradually to avoid injuries.

Although the pet obesity problem is serious, there's no reason you can't have fun. Take your dog to the dog park, play fetch or teach your pet some tricks. Who knows? Maybe you'll shed a few pounds in the process, too.