Procedures for routine clinical electroretinography (ERG) in dogs

Following pupillary dilatation and immobilization of the dog with a cataleptic drug (l-Polamivet, Hoechst) the electroretinogram (ERG) was performed with the technique of Ganzfeld stimulation. The head of the dog was kept within a sphere of 60 cm diameter, the white inner surface of which could be indirectly illuminated with a stroboscope producing light flashes of 10 musec duration. The ERG was recorded oscillographically by means of modified contact lenses. Dogs were tested for rod and cone function with luminance curves including white, blue and red stimuli and with trains of repetitive photic stimuli. Tests were performed under dark and light adaptation. The ERG of the dark-adapted dog, an indicator for the electrical activity of the rod system, was similar with that of man with respect to configuration and other characteristics. The electrical activity of the cone system was different from that of man by having a 10-fold lower sensitivity and a reduced capability for discrimination of red versus blue or white stimuli.