The first-ever canine lifetime diet restriction study has confirmed that less is better than more when it comes to feeding dogs. Results from the Purina Life Span Study shot that dogs that were maintained at 25 percent fewer calories than control dogs had a 15 percent longer median life span, or nearly two years for the Labrador Retrievers in this study.

"This 14-year study is the first of its kind to be completed using larger mammals," says Dennis Lawler, DVM, who with Richard Kealy, PhD, headed the research team. "This comprehensive study evaluated the effects of reduced food intake on body condition and a variety of health parameters, as well as life span itself. We learned from this study that feeding less doesn't necessarily change what health problems dogs encounter or what, ultimately, causes their deaths, but does influence when this occurs."

A team of scientists from Purina Pet Nutrition Research Department and specialists from universities around the United States conducted the study at the Purina Pet Care Center in Gray Summit, Mo.

Forty-eight Labrador Retriever puppies from seven litters were paired within their litters according to gender and body weight and then randomly placed in the control or lean-fed groups.

All dogs were fed the same complete and balanced diets (puppy, then adult formulations) for the entire period of the study; only the quantity provided was different. The control group was allowed to eat ad libitum during 15-minute daily feedings, while the lean-fed group was fed 75-percent of the amount eaten by its paired littermates.

• Median life span of dogs in the lean-fed group was extended by 1.8 years (15 percent) beyond the control group.
• The age when fifty percent of the lean-fed dogs required treatment for a chronic disease was 12.0 years of age vs. 9.9 years for the control group.
• The lean-fed group had lower serum triglycerides and triiodothyronine, and lower insulin and glucose responses.
• The lean-fed group had a two-year delay in the late-life loss of the lean body mass compared to the control group. (The average onset of decline was 11 years vs. 9 years.)
• As observed, the control dogs exhibited more visible signs of aging (graying around the muzzles, impaired gait and reduced activity) than the lean-fed dogs.