Five dogs presented with a history of pelvic limb lameness. On physical examination of the stifle joints, five dogs had pain, lameness, patellar luxation, or ligamentous instability. Craniocaudal and mediolateral radiographic projections revealed osteophytes or subchondral cystic lesions on the stifle joints. Based on a previously described Osteoarthrosis (OA) scoring technique, five dogs showed high OA scores. Combination of surgery and implantation of autologous adipose tissue derived mesenchymal stem cells (aAT-MSCs) or percutaneous injection of aAT-MSCs was determined with informed consent. $1{ imes}10^6$ aAT-MSCs suspended in PBS was injected in the stifle joints. The follow-ups were completed 12 months after surgery. The follow-up information was based on physical examination by veterinarians. The lameness, pain on manipulation, and OA scores improved six or 12 months after implantation of aAT-MSCs. There was a radiographic evidence of decreased osteophytes and subchondral cystic lesions. These results suggest that implantation of aAT-MSCs can be considered an option for management of cases of OA in the stifle joints.