INTRODUCTION: Duchenne muscular dystrophy (DMD) is caused by a genetic defect resulting in absent dystrophin, yet children are able to walk when small and young but lose this ability as they grow. The mdx mouse has absent dystrophin yet does not exhibit significant disability. METHODS: Allometric modeling of linearly increasing load per muscle fiber and stress on the sarcolemma with growth and exponential decline associated with loss of muscle fibers correlated with case studies and animal models of DMD. RESULTS: Smaller species or breeds are predictably less affected than large as follows: mdx mice < small golden retriever muscular dystrophy (GRMD) dogs < large GRMD dogs < humans. Case reports of combined growth hormone and dystrophin deficiency show a relatively benign course of disease. CONCLUSIONS: Future therapeutic trials in DMD might include specific growth inhibitors in combination with standard of care treatments to delay the clinical onset and reduce the severity of disease and disability.