Based on our observations gathered during ophthalmic examination of affected dogs, we propose three clinical stages of disease ranging from diffuse multifocal red / brown discoloration of the tapetal fundus without
associated visual deficits (Stage 1), to geographic retinal thinning / degeneration with mild to moderate signs of
night -
blindness (Stage 2), to more diffuse retinal thinning / degeneration affecting most of the tapetal fundus and
associated with
night - vision loss and severely impaired day - vision (Stage 3).