Is Appaloosa-specific CSNB the only thing that would cause an Appaloosa to have a “negative” ERG?
Yes. The “negative” ERG is characteristic for CSNB. There is no other ocular disease that causes the same type of ERG recording. Other diseases that damage the retina cause changes to the ERG but in a different way. For example, damage to the cells of the retina from recurrent uveitis can result in an abnormal ERG. In this situation, the ERG waveform may be a normal shape just reduced in size or it could be flat, but would not have the “negative” appearance of a CSNB waveform.
