The Purina Life Span Study was conducted at the Purina Pet Care Center in Gray Summit, MO by a team of scientists led by Richard Kealy, PhD, from the Nestlé Purina Pet Nutrition Research Department and researchers from several universities. The 14-year study, which began in 1987 and concluded in 2001, is the first completed diet restriction study to encompass the entire life span of a larger mammal.
Forty-eight Labrador Retriever dogs were paired within their litters according to gender and body weight, and were randomly assigned to either a control or lean-fed group. For the first three years, the control group was fed an unlimited amount of food during 15-minute daily feedings; afterwards they were fed an amount estimated to be the caloric requirement for large breed dogs in “normal” body condition. Each dog in the lean-fed group always received 75 percent of the amount eaten by its paired littermate. All dogs consumed the same diets, which were 100 percent nutritionally complete and balanced (first a puppy formula, then an adult formula) -- only the quantity provided was different.
Dogs were weighed weekly as puppies, periodically as adolescents and weekly as adults. Beginning at six years of age, each was evaluated annually using the Purina Body Condition System, a standard developed by Purina scientists and used by veterinarians to assess body condition in dogs and cats. They were also evaluated annually for body fat, lean body mass and bone mass and other health condition indicators including glucose and fat levels in the blood.
Read on for more about the study's findings. Then see how your dog compares.