• Flickr User: Mr TGT
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    By: Hannah Woit, Prevention

    Pets today are overeating--by a lot. Obesity is the No. 1 health threat to dogs and cats today. You may have recently heard about Meow, a cat who grew to about 40 pounds before the Humane Society intervened--sadly, too late to save his life. According to the Association for Pet Obesity Prevention, 53% of dogs and 55% of cats were overweight or obese in 2011. Excess overweight or obese in 2011. Excess weight strains a pet's heart and lungs and can lead to diabetes, as well as exacerbate orthopedic problems such as hip dysplasia, osteoarthritis, and even knee injuries.

    RELATED: Get a Downloadable List of Best Dog Workouts, By Breed

    The primary causes of weight gain in pets are the same as in humans: too much food and not enough exercise. Long hours sitting at work or in front of the TV aren't just detrimental to your own fitness. It may mean your pet gets fewer and shorter walks or less active playtime. To make matters worse, "owners think the way to show love is to feed their pet more," says Justine Lee, DVM, author of It's a Dog's Life. . .But It's Your Carpet.

  • Flickr User: LincolnStein
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    Is your pet overweight? Here are two veterinarian-recommended ways to tell. 

    1. Gently press your dog's or cat's chest with your hands and feel for his ribs. You should be able to detect them without exerting too much pressure.

    2. While your pet is standing, look down on him from above. You should be able to see a distinct waistline below his rib cage.

  • Flickr User: Svadilfari
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    If you're worried about your pet's waistline, here's how to dial back his diet today:

    RELATED: 10 Ways to Help Your Dog Workout

    Take stock of his daily food intake (don't forget treats), and cut down on the amount by 25%.

  • Flickr User: las - initially
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    Stop "free feeding" your cat. If you leave food out for her and replenish the bowl whenever it looks low, you won't be able to monitor her intake. Most cats need only 1/4 cup of dry food once or twice a day.

  • Thinkstock
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    Choose foods that are high in protein and fiber and low in fat. Experts suggest 25 to 30% protein for dogs and at least 30% for cats. (Try making these Healthy Homemade Pet Treats.) Senior dog formulas tend to have more fiber and less fat and protein. Before switching to senior food, ask your vet if these ratios are right when your dog is overweight. 

  • Thinkstock
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    Rewarding your pooch's good behavior with one or two treats a day is fine, but consider leaner options such as dehydrated protein or produce (like chicken or sweet potato) sold in pet stores or fresh produce (such as baby carrots, green beans, or apple slices). Your cat can have a few treats a day, provided you exercise her with active playtime. 

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    Next: 5 Ways To Cook For Your Dog On A Tight Budget