A procedure for recording electroretinogram and visual evoked potential in conscious dogs

A procedure for recording the electroretinogram (ERG) and the visual evoked potential (VEP) in conscious, nonstressed dogs was investigated. The animals were trained to adapt to a semirestraining support that permitted free head movement. The ERG and VEP were recorded, respectively, through contact lens-type electrodes consisting of double gold rings and previously implanted cortical electrodes. Just before the light stimulus was given, the eye of the dog was directed toward the lamp by gentle manipulation of the head. Using this recording procedure, typical waveforms of the ERG consisting of an a-wave followed by a b-wave and oscillatory potentials on the rising slope of the b-wave were recorded from fully dark-adapted dogs. During the course of dark-adaptation, the amplitudes of these waves increased and reached a fully developed shape 15-30 min after start of the adaptation. Stable ERG and VEP were recorded repeatedly for a long period of time. These results indicate that this procedure for recording the ERG and VEP is suitable for long-term visual toxicity studies of drugs in conscious and relatively nonstressed dogs.