Visual impairment can be observed at less than one year of age with severe blindness by early adulthood. Hereditary retinal degenerations (HRD) are blinding disorders characterized by dysfunction and death of rod and cone photoreceptor cells. They are genetically and phenotypically heterogeneous. Very young dogs (less than 1-year old) were affected by severe photopic and scotopic visual impairment, which progressed to more severe blindness in early adulthood.