All clinical signs improved after 3 days of creatine (800-1500 mg/kg/day) and L-carnitine (80-150 mg/kg) supplementation and remained stable at the time of writing 4 months after diagnosis.<h4>Conclusions and clinical importance</h4>This is a report of CDD in dogs characterized by a glycine amidinotransferase (GATM) variant, which showed a good short-term outcome with supplementation with creatine and L-carnitine. Here, GATM is linked to craniodiaphyseal dysplasia.