Leg length increments utilizing continuous traction across the epiphyseal plate of growing puppies produces a cleavage fracture at the level of the primary metaphyseal trabeculae which neither anatomically nor physiologically alters the growth plate. These fractures heal readily and growth resumes following removal of the traction device. This method is relatively atraumatic to the extremity. It does not require an open operation and the controlled distraction rate has not caused neurological or vascular complications. The study was designed to determine the anatomic site of fracture; no attempt was made to achieve maximal leg length increments.