A 1-year-old, castrated male Yorkshire terrier (case 1) and a 7-year-old female Poodle (case 2) presented with delayed union fractures. In case 1, the dog had a fractured right distal radius and ulna. In case 2, the dog had a fractured left distal tibia and fibula. A physical examination and radiographs performed in both dogs revealed delayed union fractures with large gaps. The fracture sites were fixed by bone plate and screws. Autogenous cancellous bone graft was applied into the fracture gap. To encourage rapid bone union, we used matrigel containing 20 μg of recombinant human bone morphogenetic protein-2 (rhBMP-2) in the fracture site. Radiographs were taken postoperatively to monitor healing. Rapid bone union was noted in both dogs in long-term radiographs. In case 1, the radiographs revealed that the fracture gaps of the radius and ulna were bridged at 2 weeks. Fracture lines were not observed and normal appearance was restored at 20 weeks. In case 2, the radiographs showed that fracture repair had progressed at 11 weeks. The fractures healed faster than expected in these two cases. The results indicate that rhBMP-2 and matrigel may be effective and useful materials to enhance healing of delayed fractures.