Implantation of different lengths of orthotopic autoclaved allograft in the femur of dogs fixed with intramedullary pin and stainless steel wire have been performed in 11 dogs, to determine the maximum percentage of bone substitution. Clinical lameness and serial post operative radiographs are evaluated, as well as, comparison of fenestrated and non fenestrated bony implants. Bone union has been observed in five dogs, fracture of the implant in three cases, limb amputation of one case, and death of two dogs during the follow up. The maximum percentage of the bony substitution that could be applied successfully is 33% with the maximum length of 6 cm. The rapid hard callus formation has been observed after the use of perforated implant.