Funduscopic abnormalities and electroretinography in cases of retinopathy in German Shepherd dogs

Objective: To perform a clinical, ophthalmological, and electroretinographic assessment of retinopathic lesions in German Shepherd dogs. Animals: The study was conducted on 14 German Shepherds diagnosed with retinopathy during the course of an ophthalmological checkup. The animals were systemically healthy police dogs used for patrolling and tracking duties and which were, at times, exposed to considerable physical strain and stress. Procedure: Periodic ophthalmological examinations using slit-lamp biomicroscopy, direct and indirect ophthalmoscopy, and photography, as well as maze testing, were performed on all dogs. Electroretinography (ERG) was performed on 10 affected German Shepherds and eight control dogs. Results: Ophthalmological examination revealed areas of tapetal hyper-reflectivity with pigmented centers, which were characteristic of inactive chorioretinitis. Most of the lesions were in proximity to blood vessels, and in a number of eyes, progression was observed during repeated examinations. Transition from active to inactive lesions, as well as onset in previously unaffected eyes, was also recorded. The ERG recordings showed impaired cone function, with significantly lower b-wave amplitudes and prolonged implicit times, in the mixed rod-cone, photopic, and flicker tests of affected dogs (P < 0.05). Conclusions: Retinopathy observed in German Shepherd dogs is characterized by areas of tapetal hyper-reflectivity with pigmented centers. The underlying causes of retinopathy in German Shepherd dogs remain unknown, although husbandry conditions and proximity of the lesions to blood vessels may suggest an association with physical exertion or circulatory disorders, respectively.