To determine whether similar changes occur in dogs undergoing retinal degeneration, we examined by qRT-PCR the levels of expression of seven P2X receptor subtypes (P2XR 1–7) and four HCN channels (HCN 1–4) in the retinas of PDE6B and RPGR mutant dogs at an advanced stage of disease (>50% photoreceptor loss) and compared them to levels in WT dogs. This evidence concerns the gene RPGR and retinal degeneration.