Objective - To observe differences in surgical and healing times as well as complication rates in dogs with a comminuted long-bone fracture stabilized with an interlocking nail (IN) using either anatomic or biologic repair. Study Design - Retrospective study. Animals - Twenty client-owned dogs with comminuted long-bone fractures. Methods - Medical records for dogs with fractures repaired during a 7-year period were reviewed; 20 dogs had repair with an IN nail and radiographic evidence of healing. These 20 dogs where divided into 2 groups, anatomic (11 dogs) and biological (9) repair, for statistical evaluation. Surgical and healing time and complication rates were compared between groups. Results - Median surgical times were: anatomic (95 minutes) and biologic (110 minutes; P = .06). Median healing times were anatomic (8 weeks) and biologic (6 weeks; P = .04). No statistical differences were observed in complication rates (the likelihood that a case required a second surgery [P = .58], the likelihood of a complication that was managed non-surgically [P = .27]). Use of a bone graft did not shorten healing times (P = .55). Conclusions - Biological osteosynthesis provides clinical advantages over anatomic reconstruction with respect to a reduction in surgical and healing time without increasing complication rates. Clinical Relevance - Highly comminuted long-bone fractures can be successfully repaired using an IN without reconstructing the fracture fragments in dogs.