¹Kafkas University, Faculty of Veterinary Medicine, Department of Surgery, TR-36100 Kars - TÜRKİYE DOI : 10.9775/kvfd.2022.27646 Th e aim of this study was to perform the "tie-in" osteosynthesis technique using an intramedullary threaded pin for the treatment of diaphyseal humerus, tibia, and femur fractures in dogs, thus minimizing rotational movements and strengthening stabilization, particularly in distal diaphyseal fractures. Th e study included sixteen fracture cases involving 14 dogs of various breeds and sexes, aged between 3 months and 12 months and diagnosed with diaphyseal humerus, tibia, and femur fractures. Depending on the size of the case, Ø2-4 mm threaded Steinmann pins were preferred for usage in intramedullary pinning and Ø2-4 mm threadless Steinmann pins placed transversal for fixation. Acrylic, rod, or fiberglass plaster was used to attach the inserted pins. Fusion was formed in all except 2 cases. It was discovered that the animals were able to use their relevant extremities without issues during the first 3 days following the operation, but aft er the 3rd day until the 15th day, the patients were reluctant to use their relevant extremities, while aft er the fift eenth day, the animals used their extremities without difficulty. Th e external fixator components used in fracture fixation were entirely removed aft er 5-7 (mean 6) weeks. In the functional evaluation, it was evaluated as very good in 9 cases, good in 4, moderate in 1, and poor in 2. As a result, it was determined that the use of threaded pins in intramedullary pinning, the first step of the tie-in method, which provides good stabilization in fracture treatment, especially in distal diaphyseal fractures. Keywords : Diaphyseal fracture, Dog, Femur, Humerus, Tibia, Tie-in osteosynthesis