A 14-year study conducted by researchers at Nestle Purina shows that a dog's median (midway between the shortest and longest) life span can be expanded by 15 percent when the dog is kept to his ideal body condition by carefully monitoring food intake. It's well known that obesity is bad for health but this is the first time that science has shown that simply by feeding to maintain ideal body condition throughout a dog's life, the length of life can be increased.

Forty-eight Labrador Retrievers were divided into littermate pairs and studied. They were given equal amounts of playtime, training and interaction with other dogs and staff members. As they aged, they were given a diet with less protein. The dogs regularly received health evaluations which checked body fat, lean body mass, bone mass and other systems.

The only difference in the way the groups were handled was quantity of food. One dog in each pair was fed 25 percent less food per day than its mate. The results, published in the AVMA Journal showed that:

Lean-fed dogs lived, on average, 15 percent or nearly two years longer, than dogs fed more food.

Dogs in the control group lived a median age of 11.2 years compared to 13 years median age for the lean-fed dogs. By age 10, seven dogs in the control group had died compared to only three lean-fed dogs. By age 12, only one control group dog was still alive as compared to eleven lean-fed dogs. By age 13.5 years, no dogs in the control group were alive, but 25 percent of the lean-fed dogs had survived.

Lean-fed dogs, on average, weighed less, had lower body fat and at senior status experienced a two-year delay in the loss of lean body mass compared to dogs in the control group. Dogs fed full food portions also showed earlier, visible signs of aging, including graying muzzles, impaired gaits and reduced activity, than the lean fed dogs.

If your dog needs to lose weight, consult with your veterinarian on the right way to help him. Cut back calories gradually and steadily. A dog who is 30 percent overweight will take six to nine months to reach his ideal body weight. Measure the amount of your dog's food -- don't guess. Do not decrease your dog's current food intake by more than 25 percent unless you're feeding a specially formulated veterinary weight reduction diet. You may create nutritional deficiencies if you cut back a regular dog food by too much.

Seniors Can Benefit Too
Even if you haven't had the opportunity to control your dog's diet throughout his lifetime, helping him lose weight at any stage is a gift. Losing excess weight helps arthritic dogs walk with less stiffness and pain. Researchers at Texas A & M University chose 16 arthritic dogs weighing 113 to 129 percent of their ideal weight and put them on a regimen of daily walks and prescribed amounts of a reduced-calorie dog food. As the dogs lost weight, they put more force on their limbs, indicating less pain. The dogs' owners reported significant improvements in mobility, such as the ability to climb stairs and jump into vehicles.