The natural bone repair processes are sufficient to effect timely restoration of skeletal integrity for most fractures when an appropriate mechanical environment exists or is created with internal fixation or coaptation. However, some situations require manipulation or augmentation of natural healing mechanisms to regenerate larger quantities of new bone than would naturally occur to achieve surgical goals. Examples include substantial loss of host bone from trauma, arthrodesis, non- or delayed unions, or insufficient healing potential of the host because of local or systemic disease, e.g. bone infection or osteocyst like lesions.Materials and strategies that are employed must duplicate and amplify the events of secondary bony formation to achieve the desired result.Bone can be regenerated through the following strategies: osteogenesis—the transfer of cells; osteoinduction—the induction of cells to become bone; osteoconduction, providing a scaffold for bone forming cells; or osteopromotion—the promotion of bone healing and regeneration by encouraging the biologic or mechanical environment of the healing or regenerating tissues. The most efficacious strategies use as many of these fundamental components of bone regeneration as possible (Figure 1). Table 1: Definition of functions of bone grafts and synthetic bone replacements. Bone graftsType: The gold standard for augmenting bone healing in humans and other animals remains autogenous cancellous bone graft. More than 500,000 bone grafting procedures are performed annually in human patients in the United States, and 2.2 million are completed worldwide. The number performed in companion animals, while undocumented, is also likely to be substantial.Classification: Bone grafts are typically classified according to the origin (i.e., autograft, allograft or xenograft), tissue type (i.e. cancellous, cortical, corticocancellous, osteochondral or vascularized), or locality of the graft (i.e. orthotopic [bone location] or heterotopic [non-bone location).Use: The cancellous bone is most commonly used in horses. It is very osteogenic and also has a potent osteoinductive capacity. Only 10 to 30% of the cells survive and only those on the surface of the graft. In horses, the cancellous bone can be harvested from the tuber coxae, sternum, and proximal tibia. Cortical bone graft is used uncommonly in horses or as part of a cortico-cancellous graft where it can contribute to the volume.The vascular response to a cancellous autograft is rapid, and the entire cancellous bed may be completely revascularized within 1 - 2 weeks. The cell population of this environment is predominantly osteoblasts, likely derived from the recipient and descendants of cells transplanted with the graft itself. Osteoblasts line the trabeculae of the graft and deposit a seam of osteoid that surrounds and entraps the grafted dead bone that is eventually resorbed by osteoclasts. Cortical grafts are revascularized less quickly than...