Progressive Retinal Atrophy (Giant Schnauzer Type) affects dogs and is an inherited eye disease. Progressive Retinal Atrophy causes degeneration of both Rod and Cone type Photoreceptor Cells of the Retina. These are important for vision in dim and bright light, respectively. Dogs affected with this disorder present with changes in reflectivity and appearance of a structure behind the retina called the Tapetum. A veterinarian may observe this during an eye exam. In addition, thinning of the retinal blood vessels may also be observed. Affected dogs have been reported with gradual vision loss beginning around 4 years of age, eventually progressing to complete blindness in most cases.