Thus, for dogs at risk from family history of developing PRA, then you can identify which dogs cannot be affected. The only dogs at risk of developing prcd are Pattern C dogs. Thus these are the only dogs for which it makes any sense to have ERGs. This result is certain, and can be used to eliminate possible incorrect or uncertain clinical diagnoses. Normally, when we think of inheritance in dogs, we think in terms of the dogs themselves, and the characteristics that distinguish them.
Some phenotypes are dominant, and some are recessive.
We understand that this is because genes exist in individuals in pairs. So, we need to think in terms of the genes that control phenotypes. The A locus, one of the genes that controls coat colour. One of several alternative genes at the same locus. Chromosomes exist in pairs in individual animals.