The retinal dysplasias (RDs) represent a group of inherited (bilateral) retinal diseases, associated with the anomalous differentiation & proliferation of one of more layers (with or without the involvement of other ocular tissues). The majority of clinical cases occur as a result of hereditary disease, however external factors such as viral infection (including Canine Adenovirus, Canine Herpes virus, Feline Panleukopaenia), radiation exposure and toxicity may induce similar changes.