A 9 year old male castrated mixed breed dog presented to the Cornell Hospital for Animals for an open wound on his right stifle five days after a surgical repair of a transverse patellar fracture. Radiographs of the stifle revealed implant failure of the wire placed during surgery, and the fragments were displaced 1.2 cm apart. The fracture was surgically reduced and a new wire was inserted to hold the fragments in apposition. Unfortunately the implant failed fifteen days later before the fracture could heal. At that time further surgical repair was discouraged and the leg was amputated. Patellar fractures are rare in dogs and are often a result of trauma. The patella is under strain at all times and repair of the bone must counteract these forces. Prognosis for patellar fractures in dogs is guarded as a large percentage of surgical fixations end in implant failure and recurrence of the fracture.