A five year survey involving an estimated 70 per cent of the Briard population in the United Kingdom has shown that approximately 31 per cent of dogs currently 18 months or older are affected with a primary retinal pigment epithelial dystrophy which causes secondary neuroretinal degeneration and blindness. The survey has defined the clinical nature of the disease in this particular breed, but has shown that it is inherited recessively and indicated that other factors may influence the age of onset, the course of progression and the severity of involvement.