Two dogs were diagnosed as atlantoaxial subluxation. One had shown sudden quadriparalysis during walking and another had shown progressive quadriparesis in 3 months. Surgery using a ventral vertebral fusion technique with bone screws and the bone cement was performed for these two cases. Preoperative neurological abnormalities, including sensory and motor dysfunctions of the four limbs and urinary incontinence, were gradually improved after about 3 months of the surgery. Although the number of cases was limited in this study, it was suggested that the ventral vertebral fusion technique was effective for improving the instability of the atlantoaxial joint in the dog.