Stargardt disease is an inherited eye disease affecting dogs. Stargardt disease is caused by the degeneration of both Rod and cone type Photoreceptor Cells of the Retina, which are important for vision in dim and bright light, respectively. Affected dogs present prior to 10 years of age with signs of vision loss including dilated pupils and decreased response to light. Affected dogs will have changes in reflectivity and appearance of a structure behind the retina called the Tapetum that can be observed on a veterinary eye exam. Additionally, thinning of the retinal blood vessels can be observed on a veterinary eye exam. Dogs may not completely lose their vision during their lifetime, but will develop significant loss of vision, especially in well-lit environments.