Tay-Sachs Disease (TSD) is a fatal neurodegenerative disorder of children and the sheep model of TSD is a powerful tool to study the disease and evaluate novel therapies. One such therapy, adeno associated viral (AAV) gene therapy has resulted in a 2-fold increase in lifespan and biomarkers are needed for clinical trials. 7T MRI shows white and gray matter alterations and MR spectroscopic abnormalities that worsen with TSD disease progression. At humane endpoint the AAV treated sheep has normalization of gray and white matter intensities, but cortical atrophy and MRS alterations persist. 7T MRI and MRS reflect TSD disease severity.