Degenerations of the dog retina: VI. Central progressive atrophy with pigment epithelial dystrophy

Abstract

(1) A series of fifteen cases of progressive degeneration of the central portions of the retina with pigment epithelial dystrophy is described; ten cases were examined pathologically. (2) Affected dogs develop a central scotoma by early or middle adult life while retaining normal peripheral vision by day and night, often for years. (3) The retinal degeneration begins overthe tapetal and dorsal non-tapetal fundus; hypertrophy of the pigment epithelium is followed by atrophy of the rods and cones and the outer nuclear layer, and sclerosis of the central retina. (4) Multicellular " nests " of pigment epithelial cells occur; they may 'be s.en in the tapetal fundus with the ophthalmoscope. (5) The electroretinogram remains normal until the later stages of the disease, when first the negative wave and then the b-wave are lost. (6) Two types ofthe syndrome are recognized: Type A, familial, in Retrievers and Border Collies, possibly due to an inherited abiotrophy; Type B, sporadic, of uncertain aetiology. (7) The pathogenesis of the degeneration and the possible role of disturbances of the blood supply in its causation are discussed. The relationship of the disease to human retinitis pigmentosa is considered.