The electroretinographic phenotype of dogs with Golden Retriever muscular dystrophy.

Abstract

OBJECTIVE: To characterize the flash electroretinogram (ERG) in the Golden Retriever muscular dystrophy (GRMD) dog and to compare the results with those from a control group of Golden Retrievers. To investigate whether similar abnormalities of the ERG as those found in a majority of human patients with Duchenne muscular dystrophy (DMD) are also observed in the GRMD dog, the canine model for DMD. Animals Five GRMD dogs and five age-matched clinically normal Golden Retrievers. PROCEDURE: An ophthalmic examination was carried out prior to performing electroretinography under general anesthesia. Rod, combined rod-cone and oscillatory potentials responses were recorded after dark adaptation. Responses to 30-Hz-flicker were recorded after light adaptation. The ERG responses of the GRMD dogs were compared with those of the control dogs by use of a Wilcoxon signed rank test. RESULTS: GRMD dogs had significantly reduced a and b-wave amplitudes after dim white flash stimuli (rod response) and reduced a-wave amplitude after bright white flash stimuli (rod-cone response). CONCLUSION AND CLINICAL RELEVANCE: The ERG abnormalities observed in the GRMD dog suggest a dysfunction in the rod signaling pathway. These ERG alterations are different from those observed in human patients with DMD.