Effects Of Diet Restrictions On Life Span And Age-Related Changes In Dogs The effects on 25% diet restriction from 8 weeks of age until death were evaluated in Labrador Retrievers, using a paired feeding experimental design. One group of 24 dogs was fed a nutritionally complete and balanced diet, and a second group of 24 dogs, consisting of sex- and weight-matched siblings of the first group, was fed 75% of the same food. Body fat mass, lean body mass, and bone mass were evaluated annually, along with serum cholesterol, triglycerides, triiodothyronine, glucose and insulin concentrations and body condition score. Onset of chronic disease and time and cause of death were recorded. Compared with control dogs, food restricted dogs weighed less and had lower body fat and lower serum triglycerides, triiodothyronine, insulin and glucose concentrations. Median time to onset of clinical signs of osteoarthritis was delayed by 2.8 years and median time to onset of clinical signs of any chronic disease (including osteoarthritis) was delayed by 1.8 years among food-restricted dogs. Median life span was increased by 1.8 years among dogs in the restricted-feeding group. Results indicate that restricting food intake is a viable means of delaying the onset of chronic disease and prolonging life span in dogs, which has important implications for improving quality and quantity of life. R.D. Kealy et al (J Am Vet Med Assoc 2002;220:1315-1320).