Clinical, electrophysiological and morphological changes in a case of hereditary retinal degeneration in the Papillon dog.

An autosomal recessive retinal disease with a late onset in Swedish Papillon dogs has recently been described. A 7-year-old Papillon dog showed no obvious signs of visual impairment and only minor ophthalmoscopic changes. Cone ERG b-wave amplitudes were within normal limits, while rod responses were nonrecordable or severely abnormal. Ultrastructural examination showed a generalized retinal degenerative disease, most prominent in the peripheral areas. The inferior retina was more severely affected than the superior areas. Both rods and cones showed morphological changes. The Papillon dog is another dog breed affected by progressive rod-cone degeneration, with similarities to the canine retinal disease given the gene symbol prcd.