Clinical Characteristics of Canine Retinopathies

Abstract

Retinopathy is a leading cause of blindness in the dog. Twenty vision-impaired dogs attended at our clinic of the National Taiwan University Veterinary Hospital (NTUVH) for ophthalmic examination and treatment. A retrospective study of these 20 dogs with a variety of retinopathies was performed. These canine retinopathy cases included progressive retinal atrophy (PRA, 45%, N=9), fundus hemorrhages (25%, N=5; two of them were associated with retinal detachment), sudden acquired retinal degeneration (SARD, 15%, N=3), retinal detachment (15%, N=3), and retinitis (10%, N=21, Sixty-five percent (N=13) of dogs were totally blind, fifteen percent (N=3) with unilateral blindness, fifteen percent (N=3) with night blindness and slight day blindness. In PRA, the cases showed clinical signs of total vision loss (N=8, 88.8%) or partial blindness (N=1, 11.1 %), retinal vascular attenuation (N=9), tapetal hyper-reflectivity (N=9), optic nerve pallor (N=9) and secondary cataract formation (N=2). Mean age (±SD) of PRA affected dogs was 5.67 ± 1.98 years old (ranged from 3.5 yrs to 10 yrs). Three SARD dogs with unknown etiology displayed quiet sudden loss of vision with no obvious retinal and central cortical lesions. Retinitis was found in 10 dogs with lesions of fundus hemorrhages, retinal detachment, or/and fundus edema. More than 50% of the affected dogs with retinitis or retinal detachment were caused by systemic disorders. Although the etiology of the disorders is not understood in all cases, three major categories of etiology are strongly suggested in the retinopathies: genetic retinal disease, acquired systemic diseases, and retinal diseases without known systemic diseases involvement. Thorough ophthalmic as well as physical examination is critical for identification of etiology and successful management of retinopathy.