These are the most common inherited illnesses in Cairn Terriers. Cairn Terriers can inherit other illnesses beyond these, but these are the most prevalent. If you are thinking of breeding Cairn Terriers, please speak with your veterinarian about potential tests that should be done to avoid congenitalCongenital means present at birth. Something that is congenital may or may not be inherited by parents and passed on to offspring. disorders in offspring.