The dominant inheritance of the "ridge" of hair typical of the Rhodesian Ridgeback breed means that dogs with either a single or double copy of the genes will appear the same, with the ridge of hair. However, those dogs homozygous (2 copies) of the gene are at a increased likelyhood to also develop a dermoid sinus. Age of onset is from birth. Symptoms can vary depending on the dermoid sinus location, and if it develops infection. Problems can include: discharge, infection, abscess, neurological problems.