Using a prospective, randomized, single-blinded clinical design, we enrolled dog owners (DOs) and their dogs presenting to a veterinary referral hospital in a two-phase trial to determine whether veterinarian-initiated counseling increases physical activity and leads to secondary health benefits for DOs and their dogs. In Phase I, self-reported health measures, height, and weight were assessed for DOs. Body condition scores (BCS) for their dogs were also determined. Owners of overweight and obese dogs (BCS > 6) were recruited for Phase II in which a baseline serum biochemical profile was obtained for DOs and dogs. Participants were randomly assigned to either a physical activity (PA) or standard care (SC) group. All DOs were provided a pedometer to determine their baseline daily step count. The PA group was counseled by a veterinarian using a standard scripted handout to encourage increased physical activity with their dogs. The veterinarian also reviewed common barriers to activity, encouraged increased levels of physical activity, and delivered a specific exercise prescription for the dog. The stated goal was for the DO to spend at least 30 minutes a day engaged in physical activity with their dog. All owners and dogs returned in three months, and biochemical and anthropometric measurements were taken again. Seventy-five DOs completed Phase I. At the completion of Phase I, 46 DOs enrolled in Phase II. Of these, 32 completed all required elements. For all participants with complete Phase I and Phase II data, there was a significant reduction in mean BCS (6.7 to 6.4; t (31) = 2.88, p = 0.007). BCS and weight decreased similarly in both groups. Glucose increased over time in the SC group but not in the PA group, yielding a significant mean group difference at followup (113 mg/dL vs. 103 mg/dL; p = 0.01). Based on our findings, both groups 325 Anthrozoös